Philips NMS 8245 evolution MSX 2+ 60 Hz

http://gilbertomsx.altervista.org/inglese/nms8245/nms8245.html

this works
did it myself too

Visit https://hansotten.file-hunter.com/. Salutations

You can try out the ROMs on an accurate MSX emulator and see if they work

Hi,

I've made a ROM for couple of friends who have wanted to upgrade their 8245 to MSX2+...

The problem with this machine is that it has only one socket for 512kb (64kB) ROM and MSX2+ normally needs at least 96kB ROM... How ever most of this extra junk is because of boot logo, Japanese keyboard interface etc. stuff that has no meaning to any European user. So... If you are ok with "MSX"-logo turned in to just "X"-logo due to space restrictions then I think I have a drop in replacement for you. (that can boot both 60Hz and 50Hz)

Drop me a mail (profile) if you are interested and include also information if you are planning to implement #F4-port while doing the mod. (likely not) Please also verify what kind of keyboard layout you have (or are these all with NL-keyboard?)

FYI: I know It is also relatively easy to mod the machine by mounting the extra ROM-chip on back of the modded main ROM chip and pulling few jump wires here and there. The benefit is very small, but in this configuration the system should actually boot using any official MSX2+ ROM set, although the localization stuff tends to go wrong.

While talking about ROMs I think that generally there is a bit too much talk about different MSX models and manufacturers. From software side the changes are none or at least next to non existing when it comes to these upgrades. Major part of this problem is how to mount the extra ROM... but as I said you can skip that talk as well if you don't care of the original logo or it's fade in effect too much.

Example video of the size reduced logo:
https://www.youtube.com/watch?v=agTKARNLQk8

Yes, the problem was that when they made MSX-BIOS + BASIC they used almost all of the 32kB they had on their disposal, so they could add only this very simple copyright message. When MSX2 was made the BASIC did not fit to 32kB anymore, so they needed to add 16kB SUB-ROM (aka EXT-ROM) How ever BASIC extensions did not take all of the space, so they decided to add this very neat MSX-logo that we know.

Now when they developed MSX2+ they run in to problems again... The new support routines needed more space and it was already used last time by the logo. It would be marketing disaster to go back to simple copyright message, so instead they moved the logo to KANJI-BASIC ROM that had some free space... This was ok solution for the Japanese market, but as European machines newer had KANJI-BASIC ROM, this kludge did not work here... How ever in MSX commercial life this was newer a problem as MSX2+ was not sold outside of Japan.

What people usually did on their MSX2+ mods here was that they soldered the KANJI-BASIC ROM on their machines anyway although they had no KANJI font ROM interface build in. This made the boot logo work and even the character extensions although when those were used, only white blocks were printed to screen due to lack of font mapper & ROM. (very difficult to add afterwards) Some mods just skipped the logo completely, but as side effect this also made stuff like SET TITLE and SET PASSWORD completely useless.

I did think about going back to simple copyright message, but that would also mean giving up with graphical mode stuff and changing memory counter, title and password stuff as well. For maximum compatibility I didn't want to change any existing code byte in ROM that was not absolutely must, so I came up with this simple logo that could be represented with mathematical ways and therefore coded in to the very small space that was left behind the BASIC extensions. It was a very byte accurate fit as this same space needed to share also some extra stuff like 50/60Hz select.

If you counted this far you may notice that we are still talking about only 48kB. The last 16kB in this case is used by the manufacturer specific disk driver. I did not want to touch that part as my idea was that you can build MSX2+ out of any MSX2 by simply dropping in new VDP and ROMs without need for mods on PCB. Later though I learned that some models still need some mods to the analog part to display the picture correctly. The VDP also needs some legs bend and jump wires soldered on top of it, if the mod needs to be done in this "no mods to PCB"-way. Each model also needs these mods for correct font and keyboard layout in main ROM unless you don't mind about wrong key caps, but those are relatively easy software problems.