|Title:||GEOS 64 2.1e Kernal ROM Image|
|This new version of GEOS kernal is bootable from EPROM.|
|Filename:||GEOS64-2.1e.rar (Click to download)|
This GEOS 64 2.1e Kernal is bootable from EPROM.
- GEOS boot in 13 seconds (power-up to first appearance of the mouse pointer).
Its performance can be watched on YouTube: https://youtu.be/CkcTa5VgADM
The GEOS 2.1e kernal eprom comes in four flavors in a .zip archive.
The geos64-21e.rar archive includes these files:
_README.TXT geos21e-4108.crt geos21e-4109.crt geos21e-7108.crt geos21e-7109.crt GEOS64.D64 GEOS64.D71 GEOS64-2.1e-Manual.odt
Desired .CRT file needs to be burned into the 27C128 EPROM (or EasyFlash).
As the names of CRT files suggest, each .crt image supports a specific setup:
geos21e-4108.crt - for 1541 drive with device no 8 geos21e-4109.crt - for 1541 drive with device no 9 geos21e-7108.crt - for 1571 drive with device no 8 geos21e-7109.crt - for 1571 drive with device no 9
In addition to real drive hardware, these EPROMs support SD2IEC.
On boot, selected eprom tries to mount either GEOS64.D64 or GEOS64.D71 image, which can be found in the geos64-21e.rar archive file.
Appropriate D64 or D71 image should be transferred to a real 5.25" floppy diskette or copied to the root directory of a SD card. As an alternative, other GEOS diskettes can be used as well. However, EasyFlash conflicts with GEOS Configure, that's why the included D64 and D71 files contain GEOS Configure_r version instead.
For EasyFlash users, it writes a small code to EasyFlash's RAM to reboot GEOS with a simple SYS from BASIC. That is, the SYS 57100 command reboots GEOS.
The sample D64 and D71 images, given with this geos64-21e.rar archive, contain the following:
Desk Top 2.0 Joystick input driver Note Pad Calendar 2016 SysInfo Convert 2.5 Preference Mgr Pad Color Mgr GeoHexCalc Calculator EggTimer2 MPS-803 printer driver Comm 1351(a) input driver Neos Mouse input driver CONFIG-r.cvt / Configure_r
. The Configure 2.0/2.1 utility changes the value of memory configuration register $01, and makes the GEOS code at $8000-9FFF unreachable (it switches ON this EPROM), causing a crash. This means, instead of Configure 2.0 or 2.1, the Configure_r (provided with the archive) should be used. So, there is a REU support but we can't configure it, without rewriting the Configure utility or permanently switching off the EPROM.
. Another systematic problem: EasyFlash and REU use the same I/O space. That is, EasyFlash uses $DF00-DFFF as RAM, and, REU has its registers at $DF00-DF0A. Therefore, it's not possible to use EasyFlash and REU at the same time unless one of them uses another I/O area.
. Although this GEOS64 2.1e version of kernal switches off EasyFlash ROM image at $8000-BFFF, it can't switch off real EPROM unless the GEOS Cartridge contains an additional logic to switch off following a write at $DFXX. That is, one can't go to C64's BASIC from GEOS without switching off the EPROM first.
. "GEOS Tricks & Tips" by M. Kerkloh and R. Tornsdorf
. "GEOS Wiki" - https://www.c64-wiki.com/index.php/GEOS
. "GEOS 64 2.1e ROM Boots from EasyFlash" - https://youtu.be/CkcTa5VgADM
|Tags:||C64, Commodore, EPROM, EasyFlash, GEOS, GEOS 2.1, GEOS 64|