What chips should be in that PCB?

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krzysiobal
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What chips should be in that PCB?

Post by krzysiobal » Sat Sep 26, 2020 6:40 am

Found it in local marketplace for 2$, thought it can be interesting as it has SIMM72 memory connector, a lot of buttons (for reuse) and sockets. The only string is: IPE-PLD.
Image Image Image

IPE might be for Instytut Podstaw Elektroniki (Institute of Electronic's Fundaments), which is the old name for one of faculties at Warsaw University of Technology (renamed in 1998.10 to ISE - Institute of Electronic Systems)
I meet the guy I bought it from once in this university, taking old garbage stuff for sale, so might be quite probable.

My guess is that this board was meant to be used for teaching purposes of Programmable Logic Devices, but I am wondering what chips were it designed to be used for.

* CON2 (SIMM72) - obviously for SIMM memory, only A0..A3, D0..D3, /RAS0, /CAS0, /CAS1, /WE are wired

* IC3, IC4 (DIP32) - probably for 32 pin SRAM (like 62512/621024 or 622048), only A0..A3, D0..D3 (shared with above), /WE, /CE, /OE wired
JP3 (top 14 pin header) has all the above signals wired
Image

* LCD1 (DIP18) - surely for two digit 7 segment, common anode (PNP transistors present) LCD display
Image

* IC6 (DIP14) - unknown, probably some arbitrary frequency generator), as the SW9 choses between it, step by step clock (SW9) and some generator, based on unknown X1 thing
Image
Image

* General purpose buttons:
SW1..SW5 - directly connected
SW6..SW7 - connected with debouncer filter
SW8 - connected with different debouncer filter
Image

* IC7 (DIP24), IC8 (DIP24), JP2 (6 pin header).
At first I thought it is some kind of JTAG, as 3 input and 1 output pins are buffered and goes only to the above chips
SIG2 -> IC8.14
SIG1 -> IC8.13, IC7.13
SIG0 -> IC7.12, IC8.12
SIG25 <- IC7.11
But the connection of
IC8.11 -> IC7.14
seems to be some kind of daisy chain
IC8 is wired to the switches

Image


* IC10 (PLCC28) - this chip controls the LCD.
Image

At first I thought it might be some PAL in PLCC package - PAL22V10 would match the GND and VCC pins, but it has NC=8,15,22,1 and here they are used
Image

* IC9 (PLCC44) - no idea what is that
Image

The only programmable chip in PLCC44 package that goes to my mind is Xilinx XC9572, but it has completely differend pinout:
Image

BTW. What is that element? It is connected between 9V and GND rails:
Image

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TmEE
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Re: What chips should be in that PCB?

Post by TmEE » Sat Sep 26, 2020 8:09 am

28pin PLCC part doesn't seem to match any display driver chips that google could show me...

I thought maybe the 44pin PLCC is an Altera MAX7000 part but power pins do not match, also Lattice Mach1/2 chips have different power pins too...maybe Atmel has anything that might fit...

Last one looks like a tantalum capacitor, 1µF 50V

krzysiobal
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Re: What chips should be in that PCB?

Post by krzysiobal » Sat Sep 26, 2020 11:36 am

TmEE wrote:
Sat Sep 26, 2020 8:09 am
Last one looks like a tantalum capacitor, 1µF 50V
Cool, thanks, so the brown one is the same kind of cap aswell, but 3.3uF 35V.

After a lot of search for programmable chips in different packages i found that:
* PLCC44 = Lattice ispLSI 1016EA (In-System Programmable High Density PLD)
* PLCC28 = Lattice ISP GAL22LV10 (this one differs from the standard PAL22LV10 by the presence of JTAG pins which allow it to be programmed in-system).

So the 8 pin header is clearly for JTAG programming (both above chips are chained together into JTAG chain)


The biggest mystery is now those two DIP24 chips (IC7, IC8):
1=+RESET, 6 = GND, 18=VCC
They also seem to be chained together and the part with buffers also is some kind of programming interface to them.


Looks like DIP24=SN74BCT8244A, a JTAG-controlled buffer that can either work like normal buffer or sniff/drive value by JTAG.
Everything clear now!
PLCC28 is responsible only for driving the LCD. Number that it gets to display comes from PLCC44 (both chips are chained by 8 wires, so probably just 8 bits of number to display $00..$FF)

Image
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ispLSI 1016EA plcc44.pdf
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lidnariq
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Re: What chips should be in that PCB?

Post by lidnariq » Sat Sep 26, 2020 4:53 pm

Any idea why they'd expose so few bits of the DRAM and SRAMs to the programmable logic?

I guess if it's a teaching board then this tiny amount is more than enough.

nocash
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Re: What chips should be in that PCB?

Post by nocash » Sat Sep 26, 2020 7:41 pm

A teaching board for learning how to access three different memory chips makes sense.
But did 32pin SRAMs even exist in 1994? If they did exist, would anybody even think about handing out such chips to students?
They might have plugged normal 28pin chips into the 32pin sockets.
The second SRAM without /WE signal looks more like an EPROM (and with less than 14 address lines since A13 seems is left floating).
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Garth
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Re: What chips should be in that PCB?

Post by Garth » Sun Sep 27, 2020 1:49 am

nocash wrote:
Sat Sep 26, 2020 7:41 pm
But did 32pin SRAMs even exist in 1994?
My 1992 Hyundai data book has up to 128Kx8 (1Mb) SRAMs, in 32-pin DIPs and SOPs. I got a 1 megabyte SRAM STD-bus board at work in 1990 or so which had eight 128KB SRAMs on it. ("STD" stands for "simple to design," not "standard.")
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