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Topic: Mega 2560 used to debug a 1978 S-100 Z80 system (Read 8196 times) previous topic - next topic

dnar

Hi guys, thanks for your comments.

I am in Perth WA.

BTW I remember looking at this very board set in 1979 when I was just 15, drooling over them and simply not being able to afford them ($800). Hence I jumped when someone on my local hackerspace email group posted it up for salvation or trash. I could not stand by and watch it trashed!

My first computer was a kit from 1977, the SC/MP based Miniscamp with a whopping 256 bytes of SRAM!  http://www.chookfest.net/computers/miniscamp.html

I am eyeing off one of several IMSAI 8080 clone kits....

Just like HiFi (with the demise of real HiFi amps, turntables etc.) computing has lost the romance of the early days....

graynomad

My first real computer was an Exidy Sorcerer

http://oldcomputers.net/sorcerer.html

Get a load of that mother board. I never had an S100 expansion chassis but did make a bank-switched EPROM board that plugged into the cartridge expansion slot so I could load my most used programs without a tape.

Another common hack was to piggy back a second set of DRAM chips on top of the main bank, bend up all the RAS (or was is CAS?) pins. solder a wire to them all and also to a spare output of a '138 decoder. That doubled your RAM.

If I could find one for low $ I reckon I'd buy it just for old-times sake.




______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

dnar

#17
Oct 27, 2014, 12:49 pm Last Edit: Oct 27, 2014, 12:54 pm by dnar
My first real computer was an Exidy Sorcerer

http://oldcomputers.net/sorcerer.html

Get a load of that mother board. I never had an S100 expansion chassis but did make a bank-switched EPROM board that plugged into the cartridge expansion slot so I could load my most used programs without a tape.

Another common hack was to piggy back a second set of DRAM chips on top of the main bank, bend up all the RAS (or was is CAS?) pins. solder a wire to them all and also to a spare output of a '138 decoder. That doubled your RAM. Mine included the RAM expansion too.

If I could find one for low $ I reckon I'd buy it just for old-times sake.




______
Rob
I owned an Exidy from around 1988 to 1992. Complete with a huge external chassis with 2 x 8" Ye-Data double sided double density floppy drives and 1 x 5" DSDD Mitsubishi drive! I think I still have the box of floppies with CP/M, Wordstar, Basic etc.

I wrote a n invoicing, ordering and stock management package in Basic to run my first bench tech business. Man, that Scorcerer ran hot! Beast.

I still have in storage a BigBoard single board CP/M system with 2 x 8" drives. The board was designed in Australia and included an EPROM programmer with ZIF socket right there on the board! Its cool, ifmit receives a CR on the first serial port after boot it redirects the console to that serial port.

graynomad

I remember the Big Board, it was a real weapon in its day.

_______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

rockwallaby

Yep, I had a Bigboard (version 2 I think) system myself. I made a special frame for it that rolled about on castor wheels, much like a small 2 draw filling cabinet.
I recall it having a single 8" drive, single sided I think and a single 5.25" Ye-Data drive.
Those were the days of CP/M and 640kB of RAM.
____
Paul
Paul - VK7KPA

dnar

Yep, I had a Bigboard (version 2 I think) system myself. I made a special frame for it that rolled about on castor wheels, much like a small 2 draw filling cabinet.
I recall it having a single 8" drive, single sided I think and a single 5.25" Ye-Data drive.
Those were the days of CP/M and 640kB of RAM.
____
Paul
64kB of RAM actually! Z80 had just 16 bit address bus. Yeah mine was like that too. The linear PSU was a beast! You could arc weld with it.

I had a Bondwell 14 luggable too, running CP/M 3 which supported banked memory. It had, wait for it, 128kB RAM!

enrlaz

OT

Hi guys,
I have heard of Ferguson Bigboard and I'm thrown here.
Since I am a fan of those old boards may you give me some pictures of your precious objects and of course every your comment or memory will be really interesting and accessible freely to my site www.vintagesbc.it (also in English language).

Make as you prefer open a new thread on this forum or answer me to my private email.
enrico dot lazzerini at email dot it

Thanks so much.

Enrico - Pisa - ITALY

dally


robwlakes

Yep I had a SCMP system too.  An original 110Baud TTY prototyping version that had 512bytes ROM and 128 bytes of RAM. Bought from National Semiconductor in Stud Road Melbourne for about $75.  A large amount for a poor starving uni student.

So going into "old timers brag mode" I used a hardware UART at the time circa 1977 to decode pure binary mentally into hexadecimal from the UART into assembly code.  Later I programmed the thing to produce an editor or monitor program as we called them back then, that could edit memory from a software scanned  hexadecimal keyboard and show the results on a 6 digit multiplexed display (AAAA DD) and also calculate relative branches all within 256 bytes of EPROM.  A 1702A EPROM from Intel if I remember correctly.  I actually telephoned Jim Rowe asking him if he was interested in this superior SCMP system, as I could see the MiniSCMP with its toggle switches and binary leds was missing the microprocessor point completely, however it fell on deaf ears.

I later moved on to the Synertech SYM-1, then the BBC 32k Model B, then the ARM based RISC OS, and still the proud owner of a working Strong ARM RISC-OS machine, and finally numerous Raspberry-Pis. I have been forced to use Intel products for most of my later working life, but now I am now very proud to be using mainly ARM based equipment (ie mobile phone and tablets).  The SCMP and 6502 lineage of lean and mean CPU performance has been largely responsible.

The BBC 32k Model B left the Apple II for dead.  It use of interrupts and relative addressing to access system I/O, language mapping etc was revolutionary.  It is a delight to see the recognition of the ARM designers respect for the economy and beautiful symmetry of the Mostek 6502 CPU.  The Acorn programmers produced some beautiful code with the 6502, it hardly surprising they should come up with its worthy successor, ARM.

 I still have the HEX code for the SCMP monitor if any one is interested, all 256 byte of it!!! :)

I am currently using my Mega 2560 board to program EPROMs for my SYM-1 system.... The Z-80 S100 projects mentioned above inspired me to do it!!!

Cheers, Rob
Learning Flute and C++, heading for a meltdown.

jelle007

This is exactly what i need in order to get my old IMSAI 5000 up and running again after 34 years
So please can you post the connection between arduino and S100 bus and also the sketch
thx
jelle.vanderlinde@gmail.com

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