Fake Foveon Adventure

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WIP: Acer Extensa 355

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Acer Extensa 355-24D



Intro

I obtained a secondhand (or thirdhand) laptop from Allegro, a local bidding site. Unfortunately, it lacks a HDD and experiences freezing issues when accessing BIOS settings. It appears to have been discarded in Sweden and bears resemblance to a different model I owned back in ~2002 - Extensa 367CDT.


I selected this laptop specifically for retro/DOS gaming/development purposes. Its compact size and easy storage were particularly attractive. Considering my tendency to accumulate electronic garbage, obtaining another large computer is not a feasible.

Laptop inside

What is inside (on motherboard):

  • LCD: LM-FG53-22NAK
  • Pentium 133 (P54CSLM) (soldered, someone reported version with Socket)
  • OMEGA Micro 82C722G - PCMCIA bridge 
  • Yamaha YMF715E - OPL3 Single Chip Audio System 3
  • m38802m2 Mitsubishi 8 bit microcontroller
  • ALI M1533 A1/9733 TS7 (Alladin)
  • Video: CHIPS T65550 B
  • near video another 2x memory chips M5M4V4265CTP (60ns?)
  • NEC D42S16165LG5 RAM chips (2MB?) (x6) I've found capacity on some blog, cant find datasheet
  • Mitsubishi M5M4V16165CTP-6S X2 On other side of MB maybe they are same size  

You can try to read yourself from the pictures:



Boot DOS (or something)

Freezing issue was fixed by removing super old (soldered) CMOS battery, replaced with CR2032 adapter. BIOS is now accessible. PATA ribbon looks damaged but works.



You need to supply "hard drive". I've used retired Kingston 1GB CF card bought in 2005 (along with Olympus E-1). Compact flash is (P)ATA compatible, (most cards works with 3.3V and 5.0V TTL). I've formatted CF to FAT16 (FreeDOS can mount FAT32 but for that size makes (almost) no difference). Sometimes there is jumper on CF/ATA adapter for MASTER/SLAVE/CSELECT modes, if it does not work out of the box, try to change this setting.

Frankenstein setup: Compact Flash + ATA adapter + USB adapter


Installing FreeDOS on Compact Flash using Windows/card reader 

So how to easily install FreeDOS on CompactFlash card (on computer without CD-ROM or FDD) using Windows 10 host? 

  • Insert CF card into compatible card reader 
  • download rufus (3.21p in my case, it has FreeDOS 1.3 system files baked into the app)
    • SET FAT16 (or FAT32 - for big drives)



  • copy FreeDOS bin files into CFcard:\freedos  folder (you can find them in downloadable freeDos iso images)
  • create fdconfig.sys file with contents (like config.sys in MS-DOS) and put to root folder of CF card. This fdconfig.sys is just example and might now work correctly in your setup.

LASTDRIVE=Z
BUFFERS=10
FILES=40
MENUCOLOR=7,0

MENUDEFAULT=1,5
MENU 1 - Load FreeDOS with JEMM386 (no EMS, max RAM free)
MENU 2 - Load FreeDOS with JEMM386 (Expanded Memory)
MENU 3 - Load Himemx only
MENU 4 - nothing

12?DOS=HIGH
12?DOS=UMB
12?DOSDATA=UMB
123?DEVICE=C:\freedos\UMBM.EXE
123?DEVICEHIGH=C:\freedos\HIMEMX.EXE
1?DEVICEHIGH=C:\freedos\JEMM386.EXE NOEMS X=TEST I=TEST I=B000-B7FF NOVME NOINVLPG
2?DEVICE=C:\freedos\JEMM386.EXE X=TEST I=TEST I=B000-B7FF NOVME NOINVLPG
3?DOS=HIGH
4?DOS=LOW
3?version=6.22


DONE - this is what is needed with minimal tools to run most games.

- Optional steps (depends on hardware):
- Yamaha DOS driver [link]
- copy DOS file manager like FAR or Norton Commander
- add it into autoexec.bat
- copy your games !

Put card+adapter into your laptop and set up boot options in BIOS.

Extra notes and strange issues

* I was unable to start Windows 3.1/3.11 with FreeDOS, you can install it, it will show up after install but if you exit to FreeDos, you will not be able to start it again ever. Maybe because: https://en.wikipedia.org/wiki/AARD_code

I've tried:
- only himemx boot
- setver.sys
- version=6.22 in fdconfig.sys (ver /R reported expected version)
(update, someone did it)

* for some reason with only HIMEMX loaded - Dos4GW games are crashing (games with replaced DOS extender - PMODE works) 


** Fun fact, Hexen was one of the first games that were not suited to run on 4 MB computer - with PMODE (that is able to use low DOS memory, another (worse) workaround was DOS4GW virtual memory by env variables) it will start and work quite ok.
"Full retard" workaround someone proposed me at the time of game release - was to start game from Windows (with swap) - but that was horrible idea.

** Heretic was meant to be played on 486... but with "-debug" command it was starting up on any 386 with enough memory (horribly slow anyway, even 386DX40+VLB was unplayable). Some 486 "like" (Cyrix/UMC) CPUs that were mis-detected or lacking specific intel 486 instructions was able to take advantage of that trick

* you can fix "small screen" in this laptop in low-resolution modes via vexp13.zip utility from 



It works ok for 320x200 but highres sucks big time, looks like nearest neighbour resize algo. It should be compatible with all CHIPS T65550 laptops. For programs in 640x480 it looks terrible.
Interestingly this VGA chip can be run in 2 modes (regarding scaling) that can be selected via BIOS setting + external monitor:
- BOTH
- Internal

BOTH means that screen will be duplicated, but the downside is that external monitor will always get 800x600 signal with 1:1 image mode (320x200 appears small) (unless expand mode is activated via cli tool).
External - if you boot with external screen connected then video mode varies and is resized/fit by display alone.

So what left for me with this laptop to do?

- fix main battery (i dumped it to trash, no time to play with it)
- find EDO RAM 144 pin to increase available RAM, maybe then play with Windows 95 setup (sadly needs original MS-DOS)
- find better screen and replace...(might be hard)

Resources:

general info about old PC's - https://www.vogons.org/viewforum.php?f=46

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