Sporniket's log on hardware stuff

Blogs & guides and tales of woo by forum members.
Post Reply
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

This week I could capture the schematics around the MFP. I planned to put the serial port too, but this one is not just wiring to IO ports, there are specialized ICs and voltage regulation curcuitery. I also had to fix the previous subsheet, with a forgotten capacitor and the parallel port and wiring incorrectly labelled with "serial" everywhere ! :oops:

As usual, the git repository is up to date.

subsheet_202-U202 — PSG and Parallel IO.pdf
(54.46 KiB) Downloaded 120 times
subsheet_203-U203 — MFP 68901.pdf
(50.64 KiB) Downloaded 120 times
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

The RS-232 port and alternate voltage generation. The "-12V" is just a hunch given that it is for the RS-232 driver. In other words, "I have no idea what I'm doing".

subsheet_204-J204 — RS-232 IO.pdf
(47.72 KiB) Downloaded 114 times
subsheet_205-U204 U205 — G12V -12V -5V.pdf
(39.58 KiB) Downloaded 116 times

Anyway, the sheet #2 is done, next sheet is the DMA circuitry (DMA, WD1772 and ports).

As usual, the github repository is up to date.
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

Here is the converted schematics for the DMA IC. The original schematics is done with the DIP-40 version of chip, and my STE has the PLCC44 version. Thus, I looked at other schematics (the Mega STE and the STBooks) to also get the pinout of the plcc version. The schematics of the STBooks seems more complete to me, as the pin 30 is annotated as "TESTIN" and wired to ground, instead of being omitted in the schematics of the Mega STE.

Another thing, on my motherboard, I fail to find a second bypass capacitor, as the plcc version has 2 Vcc pins.

subsheet_300-U300 — DMA.pdf
(54.53 KiB) Downloaded 108 times

The git repository is up to date.
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

Next subsheet, the ACSI Port, and the associated buffer/line drivers ICs.

subsheet_301-J301 — ACSI Port.pdf
(52.35 KiB) Downloaded 112 times

The git repository is up to date.

Also, this week I received the 4Mb SIMMs for STE made by @exxos to upgrade from 512Kb RAM.

2021-05-21--00.jpg
2021-05-21--00.jpg (148.2 KiB) Viewed 6220 times

I had to push harder than expected to fully engage the SIMMs in the connector. Simply place and push is not enough.

2021-05-21--01.jpg
2021-05-21--01.jpg (53.68 KiB) Viewed 6220 times

Anyway, it was a success

2021-05-21--03.jpg
2021-05-21--03.jpg (4.55 KiB) Viewed 6220 times

Now that my STE has more than 512Kb RAM, I can finally run Gembench. (And yaart tested successfully too)

2021-05-21--02.jpg
2021-05-21--02.jpg (82.48 KiB) Viewed 6220 times
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

The FDD controller and ports. The subsheet is quite full. I also took time to finally put a licence note on the page layout descriptor.

subsheet_302.sch
(26.8 KiB) Downloaded 106 times

The git repository is up to date.
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

The generation of SCLK and CLK2 was quick to do, and that's the end of the sheet #3. Next sheet deals with the GSTMCU, the shifter, and the video circuitry, it won't be so quick to capture...

subsheet_303.sch
(3.82 KiB) Downloaded 104 times

The git repository is up to date.
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

I have just finished the GSTMCU. It fits the A4 page !!

subsheet_400.sch
(26.92 KiB) Downloaded 103 times

The github repository is up to date.
User avatar
sporniket
Posts: 953
Joined: Sat Sep 26, 2020 9:12 pm
Location: France
Contact:

Re: Sporniket's log on hardware stuff

Post by sporniket »

Hum, how embarassing. It seems that recently, I have attached the kicad subsheets instead of the pdf tracing... :oops:

subsheet_302-U301 — WD1772 and port.pdf
(111.08 KiB) Downloaded 119 times
subsheet_303-U303 — SCLK & CLK2 clocks.pdf
(50.36 KiB) Downloaded 110 times
subsheet_400-U400 — GSTMCU.pdf
(117.56 KiB) Downloaded 105 times
subsheet_401-U401 — GST Shifter.pdf
(84.22 KiB) Downloaded 107 times
Post Reply

Return to “MEMBER BLOGS”