VOGONS


First post, by dionb

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Thanks to a bit of help, I now have a working EISA system at last. So it's time to populate the beast. That's not risk-free, given that OPTi Local Bus uses the exact same slots as EISA, but in an electically incompatible way that results in magic smoke being liberated if inserting the one in the other. I'm well aware how to recognise the boards, i.e. one or two brown slots in between otherwise normal ISA combined with an OPTi chipset reeks of OPTi Local Bus, whereas all slots brown with another chipset is typically EISA. Also, EISA boards have a habit of reminding you of the fact at POST - and if in any doubt you can test with ISA cards first to see that POST.

Fair enough. But the cards...

Obviously, if the card can be identified and Googled, that should generally clarify the situation. But if it can't be identified, or it can, but no authoritative info is easily available online (and no, an eBay ad saying "EISA card" isn't authoritative), or simply no internet connection is available at the time, what then? How can I determine if a given card with the typical double-depth connector wants an EISA or an OPTi bus?

Reply 1 of 12, by Tiido

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Look at power connections, they connect via fat traces and it is their different ordering that results in the magic smoke escaping.

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Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 2 of 12, by Thermalwrong

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Or you could check whether there's connection between two ground pins matching up with the EISA pinout

Looking for power traces is probably quicker though, it's a shame there's no documentation on the opti local bus that's easily located?

Reply 3 of 12, by dionb

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Theoretically I follow you, but still not sure exactly what to look for. Here's two examples:

A Buslogic/Bustek BT-747D, a known EISA card:
EISA-BT-747-BusTek-SCSI-Controller-ID531-531_3.JPG

A Chaintech ET4000 card, known OPTi:
opti2.jpg

They look pretty similar at first glance...

Reply 4 of 12, by Thermalwrong

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Thanks for the pictures, they're not something I've ever seen in person.

Try checking this pin with a multimeter, that's pin E1, which for the EISA bus is "E1 CMD# Command Phase".

On each of the Opti local bus cards I've found looking on google, that pin appears to link to ground instead:

hhV5NIB.jpg

Reply 5 of 12, by Disruptor

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A comparison between ISA slot, EISA slot and OLB slot (Optl local bus slot / Orchid local bus slot)

slot: top view, from rear to front
Name ISA EISA OLB Name ISA EISA OLB
B1 GND A1 I/O CH CK#
F1 GND CA 2 E1 CMD GND
B2 RESET DRV A2 D 7
F2 +5V CA 4 E2 START CA 3
B3 +5V A3 D 6
F3 +5V CA 6 E3 EX RDY CA 5
B4 IRQ 1 A4 D 5
F4 NC CA 8 E4 EX 32 CA 7
B5 -5V A5 D 4
F5 NC +5 V E5 GND CA 9
B6 DRQ 2 A6 D 3
F6 Key Key E6 Key Key
B7 -12V A7 D 2
F7 NC CA 10 E7 EX 16 GND
B8 NC A8 D 1
F8 NC CA 12 E8 SLBURST CA 11
B9 +12V A9 D 0
F9 +12V CA 14 E9 MSBURST CA 13
B10 GND A10 I/O CH RDY
F10 M-IO CA 16 E10 W - R CA 15
B11 MEMW# A11 AEN
F11 LOCK +5V E11 GND CA 17
B12 MEMR# A12 A 19
F12 Reserved CA 18 E12 Reserved GND
B13 IOW# A13 A 18
F13 GND CA 20 E13 Reserved CA 19
B14 IOR# A14 A 17
F14 Reserved CA 22 E14 Reserved CA 21
B15 DACK 3# A15 A 16
F15 BE 3 CA 24 E15 GND CA 23
B16 DRQ 3 A16 A 15
F16 Key Key E16 Key Key
B17 DACK 1# A17 A 14
F17 BE 2 +5V E17 BE 1 CA 25
B18 DRQ 1 A18 A 13
F18 BE 0 DRAWS# E18 LA 31 GND
B19 DACK 0# A19 A 12
F19 GND RST# E19 GND GND
B20 CLK A20 A 11
F20 +5V +5V E20 LA 30 RDY#
B21 IRQ 7 A21 A 10
F21 LA 29 BE 2# E21 LA 28 BE 3#
B22 IRQ 6 A22 A 9
F22 GND BE 0# E22 LA 27 BE 1#
B23 IRQ 5 A23 A 8
F23 LA 26 HRQ 0 E23 LA 25 GND
B24 IRQ 4 A24 A 7
F24 LA 24 M/IO# E24 GND HLDA 1
B25 IRQ 3 A25 A 6
F25 Key Key E25 Key Key
B26 DACK 2# A26 A 5
F26 LA 16 W/R# E26 LA 15 ADS#
B27 T/C A27 A 4
F27 LA 14 +5V E27 LA 13 D/C#
B28 ALE A28 A 3
F28 +5V SCLK E28 LA 12 RDY 0#
B29 +5V A29 A 2
F29 +5V LDEV# E29 LA 11 GND
Show last 43 lines
B30       OSC                           A30       A 1
F30 GND CD 31 E30 GND CD 30
B31 GND A31 A 0
F31 LA 10 CD 29 E31 LA 9 CD 28

H1 LA 8 CD 27 G1 LA 7 GND
D1 MEM CS 16# C1 SHBE
H2 LA 6 +5V G2 GND CD 26
D2 IO CS 16# C2 A 23
H3 LA 5 CD 25 G3 LA 4 CD 24
D3 IRQ 10 C3 A 22
H4 +5V CD 23 G4 LA 3 CD 22
D4 IRQ 11 BS16# C4 A 21
H5 LA 2 CD 21 G5 GND CD 20
D5 IRQ 12 BS8# C5 A 20
H6 Key Key G6 Key Key
D6 IRQ 15 C6 A 19
H7 D 16 CD 19 G7 D 17 CD 18
D7 IRQ 14 C7 A 18
H8 D 18 CD 17 G8 D 19 CD 16
D8 DACK 0# C8 A 17
H9 GND CD 15 G9 D 20 GND
D9 DRQ 0 C9 MEMR#
H10 D 21 +5V G10 D 22 CD 14
D10 DACK 5# C10 MEMW#
H11 D 23 CD 13 G11 GND CD 12
D11 DRQ 5 C11 D 8
H12 D 24 CD 11 G12 D 25 CD 10
D12 DACK 6# C12 D 9
H13 GND CD 9 G13 D 26 CD 8
D13 DRQ 6 C13 D 10
H14 D 27 CD 7 G14 D 28 GND
D14 DACK 7# C14 D 11
H15 Key Key G15 Key Key
D15 DRQ 7 C15 D 12
H16 D 29 +5V G16 GND CD 6
D16 +5V C16 D 13
H17 +5V CD 5 G17 D 30 CD 4
D17 MASTER C17 D 14
H18 +5V CD 3 G18 D 31 CD 2
D18 GND C18 D 15
H19 MAC KN CD 1 G19 MRE QN CD 0
Last edited by Disruptor on 2020-09-19, 18:46. Edited 3 times in total.

Reply 6 of 12, by Disruptor

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Conclusion: OLB cannot access addresses above 64 MB.

Furthermore, there are no GND to +5V alignments between EISA and OLB and vice versa.

Last edited by Disruptor on 2020-09-18, 19:14. Edited 1 time in total.

Reply 9 of 12, by Disruptor

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Update:
In OLB slots you cannot use IRQ 11 and IRQ 12 because D4 is BS16# and D5 is BS8#.
ISA cards in OLB slots must not use IRQ 11 and IRQ 12 (not confirmed yet).

Reply 10 of 12, by mkarcher

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Disruptor wrote on 2020-09-19, 18:48:

In OLB slots you cannot use IRQ 11 and IRQ 12 because D4 is BS16# and D5 is BS8#.
ISA cards in OLB slots must not use IRQ 11 and IRQ 12 (not confirmed yet).

Things get strange here. The OLB ET4000 card I recently acquired (which had the OLB pinout in the manual) has D4 and D5 as bus size select pins (it only uses D4 as BS16#, it does not implement driving BS8#). The OLB mainboard I own has D4 and D5 on the OPTi slots wired as IRQ11 and IRQ12. Possibly there are different variants of the OPTi local bus. I guess I need to perform some compatibility tests, as having a graphic card that randomly asserts IRQ11, and fails to notify the processor of not being able to perform 32-bit accesses is "not that great". Some more research is needed. Stay tuned!

Reply 11 of 12, by mkarcher

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mkarcher wrote on 2020-09-22, 19:26:

Possibly there are different variants of the OPTi local bus. I guess I need to perform some compatibility tests, as having a graphic card that randomly asserts IRQ11, and fails to notify the processor of not being able to perform 32-bit accesses is "not that great". Some more research is needed. Stay tuned!

Bummer! That's indeed true. If I perform a 32-bit access to my "OLB" ET4000 graphics card, the graphics card only performs a 16-bit access. Also, if I unmask IRQ11, I get a lot of IRQ11 invocations. Every access to the graphics card that does not need a split (so every 8-bit and every aligned 16-bit access) causes IRQ11 to be invoked...

This means I might need to get creative about reprogramming the PALs on that card to perform the 32-bit to 16-bit split on the expansion card, or I need to run bodge wires from the OLB slot to the processor socket, removing IRQ11 from the slot(s)...

Reply 12 of 12, by Disruptor

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Disruptor wrote on 2020-09-19, 18:48:

Update:
In OLB slots you cannot use IRQ 11 and IRQ 12 because D4 is BS16# and D5 is BS8#.
ISA cards in OLB slots must not use IRQ 11 and IRQ 12 (not confirmed yet).

mkarcher has opened this thread for further investigations on this issue: OPTi Local Bus variants