MSX2+ vs Zemmix, any real difference?

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By sdsnatcher73

Hero (646)

sdsnatcher73's picture

19-07-2019, 05:42

KdL wrote:
RetroTechie wrote:
DarkSchneider wrote:

(..) the OCM-BIOS.DAT file into the SD, to be the first file.

Why exactly is that? Loader uses sector reads rather than file read, or something like that?

IPL-ROM is a small program written in assembly that takes care of loading SDBIOS quickly, so to use as few instructions as possible it simply determines what the first file is. This software solution that was initially designed by the author Kazuhiro Tsujikawa, was maintained also in my updates because I fully agree with his choice.

@KdL: Out of curiosity and purely hypothetical: how big is that code now? And how much bigger would it be if it were to retrieve and scan the FAT to find the OCM-BIOS.DAT?

By KdL

Paragon (1236)

KdL's picture

19-07-2019, 06:36

KdL wrote:

@KdL: Out of curiosity and purely hypothetical: how big is that code now? And how much bigger would it be if it were to retrieve and scan the FAT to find the OCM-BIOS.DAT?

IPL-ROM is less than 1024 bytes, but I can't waste time on it for this kind of analysis. In the past I had removed the pletter compression introduced by caro and restored the IPL-ROM code that had become very slow. There are other components that still require a lot of work, like the VDP core. Want someone try to improve them?

By KdL

Paragon (1236)

KdL's picture

20-07-2019, 11:59

KdL wrote:
DarkSchneider wrote:

... maybe it could be advised in docs as some possible issue to be fixed manually by the user.

I thought about your suggestion, so here are the ADVICE ON SOME POSSIBILE ISSUES. ;)

All my scripts have been tested with the super administrator of Windows 10 Pro (the 'Administrator' account) and the User Account Control (UAC) disabled. Other system configurations could create issues due to the lack of elevated privileges.

The default filename of SDBIOS is 'OCM-BIOS.DAT'. This file must necessarily be the first file on the SD-Card. If after the use of the scripts some tools like RTCSAVE do not work, it means that SDBIOS has not been saved in the right way. To solve the issue it will be necessary to remove all the contents of the SD-Card and copy 'OCM-BIOS.DAT' manually as the first file.

To solve formatting issues it will be necessary to pre-format the SD-Card manually. The primary partition can be formatted in FAT16 with a maximum of 2047 MB ​or FAT16X with a maximum of 4095 MB, so you can also use an SD-Card larger than 4 GB.

To do this you may need to enable viewing of hidden and system files.

By DarkSchneider

Paladin (880)

DarkSchneider's picture

20-07-2019, 16:05

KdL wrote:

To do this you may need to enable viewing of hidden and system files.

Yes for the sdcreate inserted file. But not required if you copy manually.

Also I have to try what happens when sorting the FAT table, for the files to be shown alphabetically.

By KdL

Paragon (1236)

KdL's picture

20-07-2019, 18:42

DarkSchneider wrote:

... But not required if you copy manually.

Your statement is incorrect because the "System Volume Information" folder uses hidden and system attribute by default, the full view is also necessary to ensure that there are no other hidden files on your SD-Card if you fill it manually. Instead the action of sorting the files in alphabetical order should not be a problem for RTCSAVE but I have never tried, so I will wait for your test on it.

By DarkSchneider

Paladin (880)

DarkSchneider's picture

22-07-2019, 16:55

Good news, after sorting the FAT table the SDBIOS is loaded.

By KdL

Paragon (1236)

KdL's picture

23-07-2019, 14:31

DarkSchneider wrote:

Good news, after sorting the FAT table the SDBIOS is loaded.

Very well. The sort command was designed to quickly change the order of filenames and not the data structure in the FAT. However, defragmentation programs could cause the first file to slip and prevent SDBIOS from working properly.

By DarkSchneider

Paladin (880)

DarkSchneider's picture

24-07-2019, 10:02

I'd like to ask, anyone knows if the RTCSAVE works also on the Mist implementation of the MSX? I know it is a port of the Kdl OCM firmware, but not sure if RTCSAVE uses the SD or writes into the flash, because the flash on the Mist probably will be overwritten when load another core, so the RTCSAVE data would be lost.

By KdL

Paragon (1236)

KdL's picture

24-07-2019, 15:41

RTCSAVE writes the binary data directly on the sectors of the SD card. To load a modified SDBIOS on EPCS there are several steps to do, including conversion to HEX file and recompiling the firmware. Some conversion tools are inside OCM-SDBIOS Pack.

By KdL

Paragon (1236)

KdL's picture

03-08-2019, 17:18

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