SD512 with HB201P stucks

Supporter (13)

21-08-2018, 23:59

Hi ,
today I received my SD512 for my Sony HB201P. I have downloaded all files 8bit4ever provides on their googledrive.
There was also an 4GB Image with all Nestor drivers and Command2.com, Utils etc.
I prepared a 4GB SD card and format it with FAT16, then I wrote the image to the SD. I could read all files on my PC.
So i insert this SD into the SD slot of the SD512 and switch the 2 switches as mapper ram (both in >>RIGHT Pos.).
The I start that all in my HB201P...with no success. The maschine stucks in the blue MSX Copyright screen "MSX Version 1.0" etc.. I changed the SD card and tried many different ways of starting by pressing keys like 1,4,F4, ESC, Q, CTRL etc.
But still no boot possible. I read another post here in the forum talking about disabling the included firmware on a HB101.
The HB201P also has some application in his onboard-firmware and I supect this to interrupt the boot sequence on one reason.
Does anybody can help me doing this on the HB201P or has anybody an idear what I can do to get this setup running.

I apriciate any help and all hints.

Thx in advance Lao Mu

BTW I am new in this Forum as well as in the MSX business, but I like Retrocomputing in general. So "Hello to all!"

By odaman68000

Rookie (25)

22-08-2018, 07:25

Hi, I had same problem with HB-101.
Also HB-201 has original firmware(simple application), and it prevent the booting of SD513.

I tried anything, but there’s only one way that disabling the firmware with hirdware modification.
MSX-Bios and application firm are on different ROM chip, so only application firm ROM should be disabled.
Very easy and simple modification, but ROM pin assign and hardware knowridge is required...

By Lao Mu

Supporter (13)

22-08-2018, 16:22

Hi,
thx. I identify the chip on my maschine...it seems to be IC8 (Firmware). There is a Jumper 1 which is open in the moment

Is it enough to close it to disable that chip? [img]M:\RETRO\MSX\SD512etc\firmware_LI.jpg[/img]

BR Lao Mu

By Manuel

Ascended (19301)

22-08-2018, 16:32

Lao, you can't put a local path on your hard drive as an image link. Just upload it to msx.pics first and then link to there.

By Lao Mu

Supporter (13)

22-08-2018, 17:40

OK, I try ......is this MSX Pics here on MSX.ORG or somewhere else?

Here it is..shows the Jumper 1...is it for enabling/disabling the firmware?

https://www.msx.pics/image/ULfdE

By sd_snatcher

Prophet (3645)

22-08-2018, 18:11

Humm. I have a very different schematic for the HB-101P/HB-201P. This machine seems to have many (very) different revisions of its motherboard. Be very careful to certify that you're using the right schematic for your motherboard.

By Lao Mu

Supporter (13)

22-08-2018, 21:44

Hi, the drawing-snip is copied from the Service-manual for HB101/201 sheet 5-18.

I could verify all jumpers etc. on my board. The J1 is open and labeled with "EPROM ON" on the board.

It seems J1 open means Eprom On. So if I close it it should disable the firmware...which is the target.
One leg of J1 is connected to GND and the other to 1 (NC) & 27 (CS) of IC8 firmware eprom
Before I close J1 I will measure the voltages on J1 to GND on both sites to prevent from a shortcut
and I search about the function of this pins NC & CS.

By Pentarou

Hero (513)

22-08-2018, 22:43

J1 is used to select if the ROM chip installed in IC8 is an EPROM or mask ROM type. it's explained in page 2-2 of the service manual (see paragraph 2.2- PROVIDING OF FIRMWARE ROM).
NC means not connected and /CS means chip select.
If changing J1 doesn't work, try to remove J3 (or J5).

By odaman68000

Rookie (25)

23-08-2018, 15:26

In my opinion, jumper cut and connect cutted pin to GND with 10Kohm register.
It will disable firmware ROM completely.
10Kohm can be 1Kohm and so on, it’s just for safe, it prevent short circuit.

By Lao Mu

Supporter (13)

23-08-2018, 15:36

Pentarou wrote:

Thx for the hints with J1. I tried with J5 and receive a black screen. Also with installed SD512.

By Lao Mu

Supporter (13)

23-08-2018, 15:59

odaman68000 wrote:

In my opinion, jumper cut and connect cutted pin to GND with 10Kohm register.
It will disable firmware ROM completely.
10Kohm can be 1Kohm and so on, it’s just for safe, it prevent short circuit.

Hi,
that means you suggest to cut pin 27 from IC 8 ...am I right? As I understood You did it before on Your maschine.
What was happen then when You boot?