VOGONS


Reply 20 of 27, by alvaro84

User metadata
Rank Member
Rank
Member

It makes sense. But 8088 memory accesses are already slow enough without the chipset doing two for every request 😁

Shame on us, doomed from the start
May God have mercy on our dirty little hearts

Reply 21 of 27, by mdog69

User metadata
Rank Newbie
Rank
Newbie
alvaro84 wrote:

It makes sense. But 8088 memory accesses are already slow enough without the chipset doing two for every request 😁

Clock the RAM access circuitry at 2X CPU frequency, and speed won't suffer.

Reply 22 of 27, by einr

User metadata
Rank Member
Rank
Member

Oh, I almost forgot... My turbo XT has a really small motherboard actually. It's by Triple D International, I think it's called the TD-20, and measures only 217x166 mm -- barely larger than an A5 sheet of paper. Still manages 8 slots, too. Excuse the poor picture, I don't want to remove it from the case.

6QW5ypN.jpg

Quite an obscure board unfortunately, but quite good and modern for an XT board with explicit support for NEC V20. Runs at 10 MHz. No SIMM slots, but mine has 640K on board.

EDIT: This is actually identical to the board Mut posted earlier in the thread... Oops 😊

Reply 23 of 27, by Mut

User metadata
Rank Newbie
Rank
Newbie
einr wrote:
Oh, I almost forgot... My turbo XT has a really small motherboard actually. It's by Triple D International, I think it's called […]
Show full quote

Oh, I almost forgot... My turbo XT has a really small motherboard actually. It's by Triple D International, I think it's called the TD-20, and measures only 217x166 mm -- barely larger than an A5 sheet of paper. Still manages 8 slots, too. Excuse the poor picture, I don't want to remove it from the case.

6QW5ypN.jpg

Quite an obscure board unfortunately, but quite good and modern for an XT board with explicit support for NEC V20. Runs at 10 MHz. No SIMM slots, but mine has 640K on board.

EDIT: This is actually identical to the board Mut posted earlier in the thread... Oops 😊

Someone have sold a big amount of this Board for something around 10 dolar some years ago on "brazillian Ebay" (mercadolivre). I have bought 3 but now I have only one.

Reply 25 of 27, by 4xtx

User metadata
Rank Newbie
Rank
Newbie

Here's a compact board - also fairly well laid out
Can be expanded to 768kb apparently 😀 neat for an 8086

Attachments

  • IMG_4141.jpg
    Filename
    IMG_4141.jpg
    File size
    339.1 KiB
    Views
    59 views
    File comment
    Sharp PC-7100 mainboard
    File license
    Public domain

Reply 26 of 27, by noshutdown

User metadata
Rank Oldbie
Rank
Oldbie
4xtx wrote on 2020-10-05, 09:58:

Here's a compact board - also fairly well laid out
Can be expanded to 768kb apparently 😀 neat for an 8086

however it doesn't meet my initial requirements:

this doesn't include industrial card-style boards, it should be in baby-at form with following features: 5~6 8bit isa slots(8086 […]
Show full quote

this doesn't include industrial card-style boards, it should be in baby-at form with following features:
5~6 8bit isa slots(8086 should have 16bit isa slots)
highly integrated chipset
9*128kb ram chips or 1*simm slot(8086 requires 4*256kb simms)

Reply 27 of 27, by mkarcher

User metadata
Rank Member
Rank
Member
mdog69 wrote on 2019-04-14, 13:22:

(about splitting 8-bit accesses into two 4-bit accesses)

In order for this to work, you either need fast memory, or a slow CPU.

FPM RAM is going to help a lot here. I bet the board requires page-mode support, as page-mode access was universally implemented in RAM chips at the very end of the XT era.