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powering up a 30+ year old S100 system

Plasmo

Experienced Member
Joined
Aug 29, 2017
Messages
213
Location
New Mexico, USA
Dug out this S100 system in the back of my garage that I purchased in the early 1980's. I remember only used them briefly. I have not power it up since. One of the three boards is Cromemco 32K Bytesaver. I don't have any information about the two of the boards. Can anyone tell me more about them? Thanks.
 

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Hi Plasmo,

Well I really tried to locate these cards for you.

Never heard of Trace Memory, but I can see it's a simple Dynamic memory card

Tried hard to match the MZ80A-I/O CPU and Assembly 11-1019 legends. But nothing comes to mind. Cards with IA-nnnn are Ithaca Audio / Intersystems . You have 11. Also MZ80A is rather unfortunately close to the Sharp computer of the same name thus obscuring any Google search.

The CPU card photo is not 100% clear but looks like an Intel (i.e. non WD) floppy controller and I can see a Z80A CPU so surmise the top connectors are serial, diskette, and say another serial/parallel


AFTER A GOOD CLEANING, and checking the voltages on the relevant pin outs on the S100 Bus power rails I'd plug in the cpu card with memory and connect a PC with USB to serial converter into one of those IO ports and poweron and see if anything is printed out

Anybody else recognise this CPU Multifunction card?

regards mb
 
Thank you for looking into the boards. The pictures I took are quite high in resolution, but I think their resolution were reduced significantly when uploaded to save space. Here is the lower quadrant of the memory board. The memory are mm5257N, I think they are 4Kx1 static RAM. It reminds me very much of the Tarbell 32K static RAM board, but it is not exactly the same. Etched in copper is the date 2-20-78, I assume it was when the pc board was made.

Pic of the major components of the CPU board is attached. It is one of the more densely populated Z80+I/O board. IC date code are from 1980-1983. Etched in copper in the solder side is "CTC F 8316". I think the board was made in the 16th week of 1983
 

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I don't recognize the CPU card specifically but looking at the chips, I think the Intel chip in the center is an 8255 Parallel I/O, likely making the center 2x25 header a parallel I/O connector. The two smaller connectors are probably 2x13 headers for the Zilog DUAR/T (making them the dual serial ports). Not sure about the pin arrangement but I'd bet on a ribbon cable to a DE25F IDC-type connector; not sure if DCE or DTE so you may need a NULL modem adapter as well. A little probing with a continuity tester should prove out the parallel port as well.

I agree with amouse -- pull the cards and make sure the power supply works properly; use a Variac if you have one rather than just throwing the switch. Check the cards themselves for cracked tantalum capacitors.
 
Thank you for looking into the boards. I'm still a new member and I believe my reply a week ago was lost. Here is a repeat of it:

The pictures I have are quite high in resolution, but I think their resolution were reduced significantly when uploaded to save space. Here is the lower quadrant of the memory board. The memory are mm5257N, I think they are 4Kx1 static RAM. It reminds me very much of the Tarbell 32K static RAM board, but it is not exactly the same. etched in copper is the date 2-20-78, I assume it was when the pc board was made.

Pic of the major components of the CPU board is attached. It is one of the more densely populated Z80+I/O board. IC date code are from 1980-1983. Etched in copper in the solder side is "CTC F 8316". I think the board was made in the 16th week of 1983
 

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** Looking for the manual for this CPU board.**
I found an ad in Byte from 1981 View attachment Byte 1981-02-OCR-Page-0149.pdfshowing the cost of $349. It sure would be nice to find
a manual, but I am hatching a plan to trace the i/o port logic to find
out where all the on board devices are addressed. I have also started a
parts list and jumper config list... maybe some traffic about this board
will help jog someones memory about a manual!. This board seems to be a
great option for the core of a 4Mhz z80 system. Its too bad it doesnt
even have one blinking LED. I really like seeing leds on things like
serial activity, watchdogs, power OK.
Working on this stuff is much more fun than jig saw puzzles... maybe I
will have it figured out by the end of our current lock down.
cheers
Lawrence

MZ80A-I/O CPU ASSY NO 11-1019 REV B
u1 mc1488/75188n
u2 mc1489p/ds1489n
u3 mc1488/75188n
u4 mc1489p/ds1489n
u5 7404
u6 sn74s74n
u7 com8116 Standard Micro Systems dual baud rate generator
u8 24 pin zif eprom socket for 2708/2716/2732
u9 z80a dart dual uart
u10 am8255apc parallel port
u11 sn74ls04n
u12 sn74ls74an
u13 74ls266b1
u14 sn74ls74an
u15 sn74ls00n
u16 74ls09b1
u17 z80a ctc counter timer chip
u18 z80a ctc counter timer chip
u19 z80a cpu (z8400a ps)
u20 74ls32b1
u21 74ls09b1
u22 75ls02n
u23 74ls32b1
u24 74ls09b1
u25 74ls02n
u26 74ls244n
u27 dm74ls125an
u28 dm74ls125an
u29 dm8160n Magnitude Comparator, 8160 Series, 6-Bit
u30 sn74ls244n
u31 sn74ls244n
u32 sn74ls244n
u33 sn74ls244n
u34 sn74ls244n
u35 sn74ls244n
u36 sn74ls240n
u37 sn74ls138n
u38 sn74ls123n

q1 2n4403

vr1 lm323k 5 volt regulator
vr2 l7912cv -12v regulator
vr3 7812c +12v regulator
vr4 79l06a -6v regulator

y1 8Mhz xtal
y2 5.0688Mhz? xtal for baud rate generator 50-19200baud available in 16 steps
2 baud clocks are at 16x the baud rate set by rotary hex switches SWA SWB

J2 26 pin ribbon connecter - serial port
J3 50 pin ribbon connector - parallel port
J4 26 pin ribobn connector - serial port
J5 ??

Configuration jumpers
E1 2x9 eprom selection
E2 1x3
E3 4x1
E4 1x6
E5 1x6
E6 2x4
E7 2x6
E8 2x2

E10 1x2 not populated
E11 1x2 not populated
E12 1x2 not populated

Default config jumpers - viewed with i/o connectors at the top and
S100 bus at the bottom, voltage regulators on the left.
E1
o o o o o o o o o
| | | |
o o o o o o o o o configured for 2708 eprom

E2
o-o o

E3
o o o o

E4
o-o o o-o o

E5
o
|
o

o
|
o

o

o

E6
o-o
o-o
o o
o-o

E7
o o o o o o
| | | | |
o o o o o o

E8
o o
| |
o o


SWA hex rotary switch - serial baud rate selection E=9600 baud
SWB hex rotary switch - serial baud rate selection E=9600 baud
 
I have a couple of the Trace RAM boards, IIRC they are 32k RAM. Mine work good, after replacing a couple of dead chips. The jumpers are pretty easy to figure out. Each row of chips has one ENABLE line going to them. Left side hs four banks, and right side has four banks. The center area where the wire jumpers are has sixteen holes labeled 0 thru F. You just wire a jumper from the bank hole to the appropriate decoder hole. It appears that you board is set for the low 32K of RAM.
They are good, reliable boards. I have a manual somewhere I think.
Terry, N4TLF
 
It works .. sort of. My browser makes a big deal about it not being secure, and that it might be trying to steal information (but there is no real login required). But ... eventually I got to the site.

Roger
 
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