mnlog wrote on 2021-06-17, 05:24:

Hi there! […]
Show full quote

Hi there!

I recently bought an old Compaq CPU module with Intel 486 SL processor attached.

I though about making a simple single board computer out of it.
I planned to add some SDRAM, a PIC, PIT, UART, IDE interface and maybe RTC+battery. Everything would be controlled by an Altera MAX II CPLD. I can do without DMA.

I did something similar last year, but with an i386EX. I was able to compile a 2.6 Linux kernel, boot uClinux an run Angband in terminal.

Just expand the data bus to 32 bits, the address bus to 32 bits, connect ICs to each other and that's it, right? WRONG!

After Wikipedia: Intel 486 SL is a special low-power version of DX produced to be used in laptops. It is supposed to operate at 3.3V. So far so good. No 5V-3.3V level translation.

But I cannot find it in any datasheet or manual for it. There are tons of Intel documents on the web for other models. I can only find information on 486 'SL Enhanced' version, which is a totally different beast.

What I found is this:

1. Intel486 Microprocessors and Related Products: on p. 490 an Application Note on Migrating from the Intel486™ SL Microprocessor to the SL Enhanced Intel486 Microprocessor. The SL version was produced only during couple months between 1992-1993. The note highlights some of the SL's distinctive features;
2. The low power Intel486 SL microprocessor: a pre-conference paper briefly describing the 486 SL processor. It turns out that the SL version has integrated a DRAM controller and an ISA bus. Even better for an SBC. This goes with the fact that the 486 SL is introduced as the antecedent of 386 SL (see: Intel386 SL Microprocessor SuperSet Data Book);
3. Intel486 Sl Microprocessor Superset System Design Guide: I found this referenced in couple of Intel documents, but it is nowhere to be found. It's like a ghost. Google returns either meta information based on ISBN or links to some dubious websites.

I cannot do anything without knowing the pinout for the processor. I tried matching pins from existing DX pinouts. Even power pins are differently positioned, so no luck here.

I feel that I'm stuck. Can someone help me with ideas what to do next? Contact Intel? Or is it a lost cause and 486 SL can only be used as decoration at this moment?

I could probably switch to some 3.3V DX version, as the whole SBC is still just in concept phase.

I appreciate any help.

M

Welcome to VOGONS 😀

Do these links help in any way?

SL Enhanced Intel486TM CPU Family Preliminary Conversion Whitepaper

https://web.archive.org/web/20000818071729/ht … tel486/8517.htm

Embedded Intel486™ Processor Family Developer’s Manual

http://datasheets.chipdb.org/Intel/x86/486/ma … ls/27302101.PDF

Looks as if the Intel486(TM) SL Microprocessor Superset System Design Guide (SKU 241326-001) may have been an on-request mailout only, rather than online.

https://web.archive.org/web/19990921005052/ht … m?&sku=24132601

PC Hoarder Patrol wrote on 2021-06-17, 07:08:

Welcome to VOGONS :) […]
Show full quote

mnlog wrote on 2021-06-17, 05:24:

Hi there! […]
Show full quote

Hi there!

I recently bought an old Compaq CPU module with Intel 486 SL processor attached.

I though about making a simple single board computer out of it.
I planned to add some SDRAM, a PIC, PIT, UART, IDE interface and maybe RTC+battery. Everything would be controlled by an Altera MAX II CPLD. I can do without DMA.

I did something similar last year, but with an i386EX. I was able to compile a 2.6 Linux kernel, boot uClinux an run Angband in terminal.

Just expand the data bus to 32 bits, the address bus to 32 bits, connect ICs to each other and that's it, right? WRONG!

After Wikipedia: Intel 486 SL is a special low-power version of DX produced to be used in laptops. It is supposed to operate at 3.3V. So far so good. No 5V-3.3V level translation.

But I cannot find it in any datasheet or manual for it. There are tons of Intel documents on the web for other models. I can only find information on 486 'SL Enhanced' version, which is a totally different beast.

What I found is this:

1. Intel486 Microprocessors and Related Products: on p. 490 an Application Note on Migrating from the Intel486™ SL Microprocessor to the SL Enhanced Intel486 Microprocessor. The SL version was produced only during couple months between 1992-1993. The note highlights some of the SL's distinctive features;
2. The low power Intel486 SL microprocessor: a pre-conference paper briefly describing the 486 SL processor. It turns out that the SL version has integrated a DRAM controller and an ISA bus. Even better for an SBC. This goes with the fact that the 486 SL is introduced as the antecedent of 386 SL (see: Intel386 SL Microprocessor SuperSet Data Book);
3. Intel486 Sl Microprocessor Superset System Design Guide: I found this referenced in couple of Intel documents, but it is nowhere to be found. It's like a ghost. Google returns either meta information based on ISBN or links to some dubious websites.

I cannot do anything without knowing the pinout for the processor. I tried matching pins from existing DX pinouts. Even power pins are differently positioned, so no luck here.

I feel that I'm stuck. Can someone help me with ideas what to do next? Contact Intel? Or is it a lost cause and 486 SL can only be used as decoration at this moment?

I could probably switch to some 3.3V DX version, as the whole SBC is still just in concept phase.

I appreciate any help.

M

Welcome to VOGONS 😀

Do these links help in any way?

SL Enhanced Intel486TM CPU Family Preliminary Conversion Whitepaper

https://web.archive.org/web/20000818071729/ht … tel486/8517.htm

Embedded Intel486™ Processor Family Developer’s Manual

http://datasheets.chipdb.org/Intel/x86/486/ma … ls/27302101.PDF

Looks as if the Intel486(TM) SL Microprocessor Superset System Design Guide (SKU 241326-001) may have been an on-request mailout only, rather than online.

https://web.archive.org/web/19990921005052/ht … m?&sku=24132601

Thanks for the reply 😀

Unfortunately 'SL Enhanced' =/= 'SL'. Like I mentioned before, these are not the same and the first two documents mention only the former.

I did not know the Intel's website on the Internet Archive, so thank you very much for the link. I'll snoop around there and maybe I'll find some new information.

I did find some references in the TECHNICAL REFERENCE GUIDE SUPPLEMENT. Compaq LTE Lite Family of Personal Computers. I think that this fragments is the key point that differentiates the 'SL' from the regular 'SL Enhanced' version.

The 486SL microprocessor uses three data buses for external data
transfers. A memory bus, a peripheral interface bus, and an ISA bus are
required for external data transfers.

So we have 3 separate buses.

Also the document mentions 3 additional potential documents:

• Intel 486SL Microprocessor SuperSet Data Book -- PN 241325-001
• Intel 486SL Microprocessor Programmer's Reference Manual -- PN 241327-001
• Intel 486SL Microprocessor SuperSet System Design Guide -- PN 241326-001

From the above mentioned list I was able to find Intel486SL Microprocessor SuperSet Data Book and voila!

I think that I can continue from this point 😁 Uff!

BTW, I'm really glad that I reached out with this question, so I might find people of similar interests as mine here 😀

M