Electronics > Projects, Designs, and Technical Stuff

Experimenting with TTL Cpu, 74LS chips, old vs New? Retro style switches?

<< < (10/10)

David Hess:

--- Quote from: rstofer on June 06, 2020, 08:52:28 pm ---
--- Quote from: David Hess on June 06, 2020, 08:06:27 pm ---Even before personal computers, there were S-100 based CP/M systems contemporary to the Altair, Imsai, and similar systems which only had power and reset buttons.  They were more direct predecessors to the IBM-PC than personal computers like the Apple ][.
--- End quote ---

I have one of the CompuPro Z80 machines with a rack mount chassis.  Plain black panel with a Reset and Power switch, nothing else.  I think it was intended for industrial applications but I bought it for the blistering fast 6 MHz Z80.  I also have dual 8" floppies in a rack mount chassis.  It all worked, the last time I tried it, but it seemed strange for a system to not have switches and lights.
--- End quote ---

The one I was thinking of had the 8 inch disks in the same enclosure.  Whoa, I found a picture of it:

http://oldcomputers.net/NNC.html

Intel's Intellect microcomputer development systems came in versions which lacked all of the toggle switches and were intended to always operate from a terminal.

duak:
My first hands-on computer experience was also with an Altair 8800.  I could never get Microsoft/MITS Basic to boot up properly after it loaded.  No matter what, it always got itself stuck waiting for a character on an interface card that wasn't present.  I remember single stepping through the code as the software determined what options were needed and then modified the code in memory to correspond.  The problem ended up being a duff chip on the front panel that gated the front panel data switch states onto the data bus during the IN 255 instruction.  I seem to recall that the chip was either slow or didn't pull down its outputs low enough and so the loader code didn't see the right option.  Having a front panel that allowed single stepping operations really came in handy.

The first company I worked for professionally had developed a Z80 card and various supporting RAM and ROM memory cards for internal use.  They also developed the Break Point Logic card that allowed the developer to set up to four breakpoints, each of which could be a read, write or execute access of any memory address.  Unlike software debuggers, the BPL card could trace through ROM code because it didn't have to modify the memory location of the opcode to insert a trap instruction.

This company also started using the Intel 8086 and got an Intel development system with an ICE - In Circuit Emulator.  I wasn't on that project and never got to use the ICE.  I hear tell it had similar functionality to the BPL.

At the same company, I worked with a DEC PDP-11/23 (firmware serial monitor & minimal front panel) and a PDP-11/20 with a front panel just full of lights n' switches.  At least the latter had core memory so if I shut it off correctly, it would leave the boot loader in memory ready for the next start up.

For me, the bottom line is that it's difficult to debug something unless there is some sort of diagnostic facility like a front panel or ICE.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod