[There was another rather interesting problem in this system ... some of the debenture certificates listed explicitly the date and the amount of every payment. I of course didn't want to store every payment, but calculate it from the principal and interest rate. However some of the printed numbers (in particular from the AMP insurance company) were one cent different from what calculation would suggest. It was also impressed on me that if an incorrect payment was made the AMP was actually stupid enough to send an invoice or refund for 1c and we didn't want that to happen. I eventually solved the problem, after noticing that the problem debentures had all been issued before 10 July 1967. A chocolate fish to anyone who can tell me why, and how to fix the calculation :-) :-) ]
That was the date that New Zealand adopted decimal currency. Presumably the fact that one old penny was worth
5/
6 of a cent gave rise to rounding errors which needed to be compensated for.
That was the date that New Zealand adopted decimal currency. Presumably the fact that one old penny was worth 5/6 of a cent gave rise to rounding errors which needed to be compensated for.
Yes. Giving the precise date rather gives it away :-)
Any exact number of pounds -- or even shillings -- converted exactly to decimal currency. Most of the debentures had the principal converted to dollars and then the payments recalculated in dollars and cents. The AMP, for reasons known only to themselves, took the originally calculated payments which had already been rounded to the nearest penny, converted each payment to decimal, and then rounded again to the nearest cent. This double rounding would sometimes give a different result to calculating directly in dollars and cents and rounding once.
What a pain!
But easy enough to compensate for, once understood, with a flag on each loan indicating whether this had been done.
Regarding the 0 vs O (zero vs letter O), the first computer I built in the mid 70s was based on the GI LP8000, a dim ascendent of the PIC. It was programmed directly in machine code hex, usually hand written on paper first. For some reason which I don’t know, instead of uisng standard hex nomenclature 0-9, A-F, the standard was to use 0-9, J-O, called “modified hex”.
I guess it was perceived to be ever so slightly easier to convert the J-O to and from ASCII as you could do it without adding: it seems bizarre nowadays, but that was the mindset back in the day.
Of course, it was going to be a minefield between 0 and O in machine code hex listings. The solution was to use both a slashed zero and the letter O was written as a square. When verbally discussing a listing, the letter O was always said as “square”. In context, to a trained programmer fluent with the instruction set encoding (a very common skill then, not at all nowadays), it was pretty universally obvious in context whether it should be 0 or O.
I think the idea was that "J" is the tenth letter in the alphabet. I remember seeing some hex dumps using that nomenclature. It also brings to mind the hex-vs-octal arguments at my high school... "numbers don't have letters, period!"... I was always more comfortable with hex myself. By the time I got to college, it didn't really matter. Later, I found it pretty funny that they created a "pre-computer science" "weed out" course that was essentially nothing but "number bases, get it or get out". As I understand it, a lot of people flunked or dropped that class.
I guess it was perceived to be ever so slightly easier to convert the J-O to and from ASCII as you could do it without adding: it seems bizarre nowadays, but that was the mindset back in the day.
The Bendix G-15 and others used Sexadecimal, with UVWXYZ instead of ABCDEF. The G-15 was a vacuum tube and drum computer from about 1958.
Jon
The Bendix G-15 and others used Sexadecimal, with UVWXYZ instead of ABCDEF. The G-15 was a vacuum tube and drum computer from about 1958.
And the Librascope LGP-30, a vacuum tube and drum computer from 1956, used the digits "FGJKQW", because that's how the characters' binary codes fell on the Flexowriter... Easily remembered as "fiber glass javelins kill quite well".
Thank you for posting the picture of the chiclet pet commodore. That was my first computer that I payed for and owned. What a sweety with that great look and a auto cassette data input. Way better than the 100 buss system with the cold cold boot from a line of with switches. The top of the pet lifts up somewhat like the hood of a car with a metal bar to keep it up. This way you could stare at the mother board and power supply. That was a nice computer for it's time.
The pet was donated to the vzekc and should be turned into a fully functional computer.
The pet was donated to the vzekc and should be turned into a fully functional computer.
One question comes to mind, WHY?
Sega SC3000H, but it probably should have been a C64.
I had no support for it, no magazines, no new games, no local club, and couldn’t really learn anything outside of the manual.
So the Amiga, I’d like to think of my first computer, because I had friends with them, one of which at least tried to tech me programming.
Strictly speaking, my first computer might have been a serious mechanical adding machine given to me as a kid.
First used was a ZX81 (later with 16k expansion) in about 1981. Wrote first code on a ZX Spectrum 48K - 1982
First owned a Spectrum 48K Plus 1984-1985 ish, then Amstrad CPC464, CPC6128, Amiga 500, Amiga 1200... long break... Pentium Celeron 600Mhz (circa 2000).
First computer I bought was.. an Oric 1, and I still have it
Lulled by the advertisment of 64k memory (compared to the 48k of the Spectrum) but not realising that extra 16k was used by the system! Probably the worst keyboard of any home computer of that age. Anyway, I took some pics for your amusment.
The first computer I ever OWNED was a home-built "pineapple" in 1981. It was an unauthorized copy of the Apple ][ main board and then I built it with parts bought/scrounged. Afterwards it was expanded with a genuine floppy drive and a cheap crt monitor. It had a MTBF of about 4 hours so backups had to be religiously done often.
I learned the value of backups the hard way. Once when I was working on a sizeable BASIC program the CPU decided to crash and wipe my only floppy copy of my program. This was after about 3 weeks of work on it. I couldn't look at it again for a couple of days so went out on my bike a saw a few movies.
The first computer I ever USED was a PDP-8 in 1967. That one was completely assembled into an ad hoc rack frame by one of the electronics teachers at my high school in Ottawa. Ours was the first school in Ottawa to ever have a real computer. That teacher, Carl Weick worked on the Avro Arrow, the only Canadian fighter jet to intimidate the US military and president into demanding its program be cancelled and all materials destroyed. To PM Diefenbakers' discredit, he did just that.
Too bad I have no pictures of either of those computers.
As for stuff waiting to be fixed I have a Fat Mac (512K RAM, floppy only, no HDD) which worked last time I tried it maybe 6 years ago and an external 45 Mb HDD which won't spin up.
I built a few "Orange" clones of the Apple II and sold them for a few $'s spending extra money.
My first computer was a Sinclair ZX80, quickly followed by an 81 with "Drum Roll...." 16K RAM PACK!!!
WOW... 16K, that was a HUGE memory :-)
Not long after that I had a VIC20, then a Commodore 16+4.
I went through a succession of second hand machines bought from the wanted ad's and such like (Early 80's) I had an Atari 800XL, Tandy TRS-80 among others, and that was until I discovered...
THE BBC MODEL B Micro
That was my first computer LUST... I saved money like it was going out of fashion. Birthdays, Christmas, Paper Round etc then it arrived.
16 Colours, 4 Channel sound, More I/O than I could shake a stick at, I was in heaven, it was my first real computer and I paid for it ALL myself, so I didn't have to share it with my sister or the rest of the family.
Up until I left school and got dragged kicking and screaming into the world of the IBM Compatible/Clone and Dos/Windows I stuck with Acorn.
BBC B up to a Master, then an ET Turbo, and eventually with the pay check(s) from my first summer Job an Acorn Archimedes A5000
I had to get rid of all my BBC Stuff about 10 years ago, when myself and my wife moved to the house we now have, it broke my heart to see it all have to go. Some of it went to new owners, but a big chunk went to the breakers yard too :-(
I do however, still have my A5000, but she's in a sorry state these days. The CMOS Ram's buggered on it after an Alkaline battery leak, I removed the battery and soldered in a double A twin holder, but to no avail. Board outside looks fine so I suspect there's track damage inside the layers somewhere. It powers up, but beacuse it has no settings, and I can't make it store anything, I'm really not getting it to do much more than give me a supervisor * prompt.
I'll get the time to fix it one of these days however :-)
Aside from that, I have a server rack full of modern day PC's but I do still have a few gems kicking about in my workshop.
Got an original Sun Netra T105 Blade server somewhere, and an original set of Solaris/Sun OS disks somewhere for it, and got various bits and bobs Iv'e picked up at car boot sales with the intention of junking them for interesting parts.
I'll always have a soft spot for Acorn though, British Designed, British Made, British Invented. IMHO Opinion, Acorn should get so much more recognition than they actually do, after all, the world would be a very different place today without the ARM Processor.
:-)
Those old dual layer boards are easy to trouble shoot, just put a bright led light source behind then and you can usually see broken tracks quite easily.
E.g.
My first computer was an Apple II with two floppy drives and a green monochrome CRT. I don’t know how much RAM it had, but I can remember playing »Lemonade« and »Nibbles«.
I still have this unit but it is sitting in storage at my parents place and has not been turned on for at least 25 years.
Those old dual layer boards are easy to trouble shoot, just put a bright led light source behind then and you can usually see broken tracks quite easily.
E.g.
Heck, where
is the broken track?
(And which 68000 machine is that, anyway?)
Thanks, nice photo!
Those old dual layer boards are easy to trouble shoot, just put a bright led light source behind then and you can usually see broken tracks quite easily.
E.g.
Heck, where is the broken track?
(And which 68000 machine is that, anyway?)
Thanks, nice photo!
To the left of the 40 pin ROM socket.
That's a rev 4.5 Amiga 2000 motherboard.
I don't know what the first computer I used was as it was a main-frame and I had a pre-university job at Scicon back in 1979. I learned to program in FORTRAN on punched cards and these were loaded by computer operators. I often wonder what became of all the computer operators when their jobs disappeared.
The first computer I owned was a BBC micro model B with a cassette player for storage. It took five minutes to load games and then the cat would jump on the keyboard and you'd have to start again!
My present workstation (which is 8 years old) has nearly a million times the RAM (24GB vs 32k), over a 1000 times the CPU speed (3GHz vs 1MHz) with 8 times the core count and a million times the hard-drive storage yet it takes longer to boot up than my BBC micro did!
My first computer was an Apple II with two floppy drives and a green monochrome CRT. I don’t know how much RAM it had, but I can remember playing »Lemonade« and »Nibbles«.
I still have this unit but it is sitting in storage at my parents place and has not been turned on for at least 25 years.
I'll give that a try thanks.
I did however have an interesting Idea Last Night.
The RTC/Cmos chip in the A5K is an PCF8583 which is an I2C based device.
I know what the I2C address of it is, as it's in the programmers reference manuals, so I got to wondering if I could just remove the SMD that's on the mobo, and wiring the I2C lines SDA/SCK and GND directly to an Arduino Nano/Micro or similar. I know which 3 lines I need and where to get them, and importantly I know there active, I also know where to get a 5v supply from to power the Arduino.
My thinking is to program the Arduino to be an I2C slave, on the address the computer looks for the RTC chip, then just let the Arduino save the settings and such like in it's on board Eprom.
In all honesty, I'm really not too bothered if the clock actually keeps the correct date/time, the important part is that the system settings are saved, and looking at the data sheet for the RTC chip, i recon I can quite easily emulate it using an Arduino, or even just something like a DSPIC (I have a few of those lying around too)
Anyway, it's all just theory at the moment, like everything I want to do for me, it'll end up going on the "Stuff for my Retirement" pile :-D
SECOINSA (FUJITSU)
SERIE 20 AT School (cobol & Fortran with IBM 8" disk recorder , Sharp mz80b that I ever love (ever searching on ebay) at local computer club an finally zx-pectrum 48k at home, some years after Amiga 1000 for C & 68k assembler and Now!! ORIC ATMOS only for nostalgic, non rational things
My first computer was an Apple II with two floppy drives and a green monochrome CRT. I don’t know how much RAM it had, but I can remember playing »Lemonade« and »Nibbles«.
I still have this unit but it is sitting in storage at my parents place and has not been turned on for at least 25 years.
I'll give that a try thanks.
I did however have an interesting Idea Last Night.
The RTC/Cmos chip in the A5K is an PCF8583 which is an I2C based device.
I know what the I2C address of it is, as it's in the programmers reference manuals, so I got to wondering if I could just remove the SMD that's on the mobo, and wiring the I2C lines SDA/SCK and GND directly to an Arduino Nano/Micro or similar. I know which 3 lines I need and where to get them, and importantly I know there active, I also know where to get a 5v supply from to power the Arduino.
My thinking is to program the Arduino to be an I2C slave, on the address the computer looks for the RTC chip, then just let the Arduino save the settings and such like in it's on board Eprom.
In all honesty, I'm really not too bothered if the clock actually keeps the correct date/time, the important part is that the system settings are saved, and looking at the data sheet for the RTC chip, i recon I can quite easily emulate it using an Arduino, or even just something like a DSPIC (I have a few of those lying around too)
Anyway, it's all just theory at the moment, like everything I want to do for me, it'll end up going on the "Stuff for my Retirement" pile :-D
BIG THUMBS UP TO A FELLOW BEEBER :-)
My first computer was a Sinclair ZX-81. I loved programming that semi-toy. I got the infamous 16KB expansion dongle: the connector was so flimsy you couldn't move even the slightest. Otherwise you got a beautiful system reset.
Next was the obvious step: Sinclair Spectrum 48K. I used it very thoroughly and even programmed a financial program using "Microdrives" that was used commercially by a friend's firm. I ended installing the guts inside the keyboard of an old AS/400
It worked very fine!
My first "proper" computer was an IBM Portable 5155. 15Kg of portability, go figure! The system was only 256KB RAM and I hacked it to 640KB. In Bill Gates' own words: "640KB is all you'll ever need for RAM". It had two 256KB 5 1/4" floppy drives. Later I added an IBM 5161 "PC Expansion" that was the size of an IBM Personal Computer, with a 10MB disk drive. In IBM's own words: "10MB is all you'll ever need for file management"
Then I got an IBM XT-286, a strange mix between an IBM-XT case and IBM-AT guts, only a bit faster. That was the sexiest XT-286 in the world
: It had a 20MB disk drive, 16MB RAM, 2MB "Expanded" memory option, 287 Math coprocessor, External tape backup system, Token Ring adapter, VGA adapter (IBM 8515 monitor), Monochrome adapter (IBM 5151 monitor) for a dual display system, SoundBlaster, IBM ProPrinter 4201 and other options I no longer remember... all card expansions were used. You couldn't expand it any more!. I still have it.
The next computers were a lot less glamourous
My first "proper" computer was an IBM Portable 5155. 15Kg of portability, go figure! The system was only 256KB RAM and I hacked it to 640KB. In Bill Gates' own words: "640KB is all you'll ever need for RAM". It had two 256KB 5 1/4" floppy drives. Later I added an IBM 5161 "PC Expansion" that was the size of an IBM Personal
Actually the 640k quote is a well reproduced myth. The 640k limitation was instead based on the architecture of the IBM PC that put the graphics memory starting at A000:0000 (the mono card put the text at B000:0000 and the colour card put the text at B800:0000). If you could forgo graphics, and used a CGA for text only, you could happily make a PC run with 736k of RAM. Later invocations of MS-DOS (6 IIRC) allowed you to load TSR programs "high" (using LOADHI), and you could map RAM into the D000:0000 and E000:0000 spaces (C800:xxxx was used by HD controllers)