DS990/1 Boards from Estate Auction

[+FarmerPotato]

I've unpacked the DS990/1 boards from the auction.

 

They are:

 

Full size cards:

 

1. CPU card with TMS9981, Date code 7951. 10 MHz (max for 9981)
2. 64K memory card with 18 TMS4116s (parity bit!)
3. VDU Controller with TMS4710 ROM
4. Floppy disk controller interface (2x same board#)  with ROMs 1700-1  -2  -4,  1703-1  -2. The dumps on bitsavers are mostly 1 bit set per byte.

Half-size cards:

(The backplane edge matches the right half of the full size cards.)

1. Power supply; 4 wire in.
2. 2x Board with two 3" long capacitors, one 3700 uF
3. Board with 8-bit serial-in parallel-out register; no external connectors

 

Numbers   Diagram/Schem   PWB/Board#      Assy            Serial     Chip Date Codes
CPU       2270082 A     2270081-0001 B   2270080-0001 E   5118          8025-8105 (7951)
Disk      2267352-0001  2267351-0001                      05098         7927-7936
Disk      2267352-0001  2267351-0001                      x2021         7945-8007
VDU        993422        993420-0001      993420-0005K    011020 R4     7832-7845
64K RAM   2267362       2267361-0001     2267360-000      081355        7945-8005

VDU has a socketed PROM dated 8004

CPU card has a lot of unpopulated IC pads.

 

It has one ROM U29 2270124-0003. U28 unpopulated.
U19 is a DIP40. pin 23 VCC, pin 1 GND.   

Nearby: 12 MHz crystal, unpopulated 2x13 header with 3 power pins.

 

From the manuals on bitsavers.org,  I guess these would make up the rest of a DS990/1 system:

1. Communications Interface
2. Expansion Memory option
3. Disk Drive I/O Processor  (in addition to the disk interface!)
4. Cartridge Control (tape)
5. "P18"
6. Printer Control

 

Since I have no chassis (those parts were pickup-only!) I have no plan for these components.

Got retake my PCB photos, but here are the auction listing photos

 

 

 

Edited March 26, 2022 by FarmerPotato

[jbdigriz]

Definitely interested in those photos, the half-size cards too. Thanks for posting.

 

jbdigriz

[kl99]

welcome to the owners group

here is mine

http://www.ti99.eu/?page_id=4416&lang=en

 

[+FarmerPotato]

Some photos of DS990/1 boards:

 

CPU

 

                                    

 

 

 

64K DRAM 

 

    

 

Floppy Disk Controller (2 copies)

 

    

 

    

 

 

VDU Controller

 

    

 

Smaller board

 

  

 

    

    

 

Edited March 27, 2022 by FarmerPotato
Add 5 photos

[jbdigriz]

On 3/25/2022 at 10:44 PM, FarmerPotato said:

Some photos of DS990/1 boards:

 

Thanks! I'll pull the boards out of my /1 when I get a chance and compare them. Those half-sized cards do look like the power supply boards in mine, though, iirc.

Edited March 29, 2022 by jbdigriz

[+FarmerPotato]

5 hours ago, jbdigriz said:

Thanks! I'll pull the boards out of my /1 when I get a chance and compare them. Those half-sized cards do look like the power supply boards in mine, though, iirc.

Would like to know if your CPU card has just 1 EPROM at U29, or U28 populated as well?

Guessing that U29 is a 2532 under the sticker: "2270124-0003"

 

U30,31 are TIM9905 (LS251) data selectors

 

U14,U15 are uPD2114 or 4Kbit SRAM, so it has 1024 bytes of RAM to work with (the expansion card is 64K)

 

 

 

I am able to read something in the first 2K by reading it as 2732.  (The A11 pin of 2532 is the E* of 2732 so it's 0. Need to make a read-only 2532 adaptor.)  TMS9981 has an 8-bit data bus, so one EPROM should be the whole width.  If U29 is for booting at base 3000, or maybe it's paged--then I'm unable to see its LOAD vector at 3FFC. 

 

The 2k that I got out doesn't look too sensible.   There are chunks of BxxBxxBxx which look like unlinked object code!?!  I see no readable strings. Disassembling it, I did see a long, almost coherent stretch of code with chunks like this:

           MOV *R4+,R3
LABEL1 C *R4+,R7
          JEQ LABEL2
          DEC R3
          JNE LABEL1
          .. do some stuff with moving registers
          .. jump way down further
LABEL2 ... move some data *R7...
         ... another weird for-loop

 

My wild guess it is  copying initial values of variables from ROM to RAM.   Maybe it is a self-test. There ought to be some boot loader for floppy--the floppy controller doesn't have a code ROM on it.  But I'm missing the Floppy I/O Interface, maybe that had a ROM?  Else, the DSR for FD1000 was in TXDS or whatever OS.  I've been reading about the Device Independent I/O and File Manager in TXDS for context. 

 

 

 

 

 

 

[+FarmerPotato]

My interest in this card is to learn from the PCB layout.

 

The PCB card edge is 3.9mm or 0.154 inches, 43 fingers wide (86 trace) then a 0.5" notch.  Like these still made by EDAC.

Counting pin 1 at the CPU end, odd numbers on the component side:

1 GND

2 GND

3 VCC

4 VCC

5 VCC

6 VCC

8 VDD (on TMS9981)

20 GND

72 GND

85 GND

86 GND

 

In the top middle of the CPU board is an unpopulated area.  My guess (hope?) is this is for a test/debug interface.

 

Unpopulated spots for 2x13 pin header,  R5-R11, jumpers E7-9, E10-13, several more DIP14s. 

 

U19 DIP40 was not able to guess a chip from VCC and pin 26=GND .  Pins 29-36 are probably the data bus.

 

U20 DIP20.  I guessed maybe a 9902, remembered that 9902 is DIP18, and that only I put it in a DIP20 with a decoupling capacitor. 

 

 

 

[jbdigriz]

On 3/29/2022 at 9:29 PM, FarmerPotato said:

My interest in this card is to learn from the PCB layout.

 

The PCB card edge is 3.9mm or 0.154 inches, 43 fingers wide (86 trace) then a 0.5" notch.  Like these still made by EDAC.

Counting pin 1 at the CPU end, odd numbers on the component side:

1 GND

2 GND

3 VCC

4 VCC

5 VCC

6 VCC

8 VDD (on TMS9981)

20 GND

72 GND

85 GND

86 GND

 

In the top middle of the CPU board is an unpopulated area.  My guess (hope?) is this is for a test/debug interface.

 

Unpopulated spots for 2x13 pin header,  R5-R11, jumpers E7-9, E10-13, several more DIP14s. 

 

U19 DIP40 was not able to guess a chip from VCC and pin 26=GND .  Pins 29-36 are probably the data bus.

 

U20 DIP20.  I guessed maybe a 9902, remembered that 9902 is DIP18, and that only I put it in a DIP20 with a decoupling capacitor. 

 

 

 

OK, sorry to take so long getting to this, but I knew there was something bugging me about your CPU board. Finally got a chance to pull my boards out, and that is actually the I/O processor board with the 9981. Mine has a 9900; that's what threw me. Here's front and rear shots, ASSY 2267355-0001, Schematic 2267357, U9 3596-6 U11 3596-5. I will get to dumping those roms sometime, and the rest as well.

 

 

 

 

[jbdigriz]

Here's the actual CPU board, ASSY No. 993415-000. There what looks like an  empty rom socket, but I don't think the 990/1 uses it; it loads the OS using the boot roms on the 64K board. Again, I'll get to roms later. Back to work for now.

 

Oh, your half-cards look like mine except in much better looking condition. The electrolytics have leaked on the 5V supply here, and badly leaked on the 12V(I think.) Probably have to completely rebuild that one after cleaning, and maybe the 5V. The aux supply with the 4-pin looks okay. Everything was working on this system when I fired it up, uh, quite some time ago. Sad 😞 Look on the bright side though, it could have easily ended up in the dump. Not by my doing though.

Edited September 16, 2022 by jbdigriz

[jbdigriz]

Also, those are the ONLY 3 boards in the power supply cage in my system. Since no printer or tape drives  to power, of course. There is a big xformer up front by the keyboard and looks like another smaller one  in the back of the PS cage that looks like the ones on the boards. 

 

One more thing, the diskette loader PROMs on my 64K board are U63 (2267371-1 HI 4K) and U64 (2267371-2) LO 4K. Can't quite tell what's on yours, but worth looking into, I'd say.

Edited September 16, 2022 by jbdigriz

[Jimhearne]

On 3/30/2022 at 2:29 AM, FarmerPotato said:

U20 DIP20.  I guessed maybe a 9902, remembered that 9902 is DIP18, and that only I put it in a DIP20 with a decoupling capacitor. 

 

I believe the reason a 20 pin socket is often used for a TMS9902 is that there is also the TMS9903 Synchronous Communication Controller which is pin compatible apart from having 2 extra pins.  

So by using a 20 pin socket the board can handle a 9902 or a 9903

 

Edited September 20, 2022 by Jimhearne

[Jimhearne]

Hi FarmerPotato,

I've just realised that some of these boards are probably what i need to upgrade my model 915 terminal  (seems to be the same as a 770 or 771 terminal) to a DS990/1

 

If you want to sell them at some point please let me know.

 

Many thanks,

 

Jim 

 

 

[+FarmerPotato]

@Jimhearne
Yeah, I’d sell you the whole lot. I doubt I will be able to put together a whole DS990/1.  I’d rather expand my TM990/101, or wait for a 990/4 or better.  That said, I’d be happy to trade for TM990 parts!

 

And I’ve just bought a stand-alone Speech Evaluation Module, the one with TMS5220C and a serial console Forth running on a TMS7000.

 

 

 

 

 

 

[jbdigriz]

Good deal if you guys work something out. Finishing up the /10A General Description here. Issues creating an outline for the PDF, but on track to getting it done.

[Jimhearne]

Here are my main boards from the 715 terminal.

Top then bottoms.

Edited September 21, 2022 by Jimhearne

[Jimhearne]

And then the 3 psu boards.

Top then bottom.

Weird double ended caps on these.

 

[jbdigriz]

Trying to source those caps. No luck so far.

 

Those roms need to be archived if you can. My next project is dumping roms on a number of machines and boards. Will post when available. Well, that and reverse-engineering some /12 microcode to see if I can figure out how the microcode assembler and binary object conversion for the WCS work. 

Edited September 21, 2022 by jbdigriz

[+Ksarul]

Jensen is apparently the only company currently making four-pole axial electrolytic capacitors. All other vendors apparently stopped making them in the late 1980s. Here's a current data sheet on them.

Jensen-4-pole-capacitors-data-sheets.pdf

[Jimhearne]

10 hours ago, jbdigriz said:

Trying to source those caps. No luck so far.

 

Those roms need to be archived if you can. My next project is dumping roms on a number of machines and boards. Will post when available. Well, that and reverse-engineering some /12 microcode to see if I can figure out how the microcode assembler and binary object conversion for the WCS work. 

The caps look fine on my boards and the boards are working, so if FarmerPotato is agreeable maybe you could buy the 3 psu boards and i'll buy the rest.

 

Do we know the pinout of the Roms ?, i've a Minipro if they are standard, or if they are something funny, i can hook them up to a PIC dev board and read them off.

 

Jim

 

Edited September 22, 2022 by Jimhearne
Pressed the wrong button !!

[Jimhearne]

8 minutes ago, Jimhearne said:

 

Do we know the pinout of the Roms ?, i've a Minipro if they are standard, or if they are something funny, i can hook them up to a PIC dev board and read them off.

 

Jim

 

Never mind, found them TMS4732

Looks like a socket to socket adaptor will let them be read in the minipro. 

Programable polarity chip selects, that's a new one on me.

 

Jim

 

Edited September 22, 2022 by Jimhearne

[jbdigriz]

2 hours ago, Jimhearne said:

The caps look fine on my boards and the boards are working, so if FarmerPotato is agreeable maybe you could buy the 3 psu boards and i'll buy the rest.

My budget is shot right now and I'm trying to scrape up enough to pay postage on the rest of the manuals that the source of the /10A manual has, and get a large format scanner. That's the top of the list right now, but if I can't find replacement caps I will certainly keep FarmerPotato in mind if you don't want them as spares.

 

[jbdigriz]

 SomeComputerGuy in Austin noted this basket case 771 on the Classiccmp Discord yesterday. Completely unrealistic starting bid considering the sad shape of the CRT and the obviously leaking capacitors on the regulator boards. Hard to believe the seller even tried to power it up. That said, a group buy for a parts donor machine might be an option if there are enough people interested and they'll take a reasonable offer. The case, keyboard, maybe the logic boards and backplane are probably useable. Broke right now, myself. https://www.ebay.com/itm/134411816138 Plenty of useful pics, though, and btw, @FarmerPotato, @jimhearne it does use that TMS9981-based I/O processor we couldn't find docs on, so Jim should be good to go on that.

Edited January 14 by jbdigriz