Description:

This new version of GEOS kernal is bootable from EPROM.

This GEOS 64 2.1e Kernal is bootable from EPROM.

It features:

- GEOS boot in 13 seconds (power-up to first appearance of the mouse pointer).
- SD2IEC support to mount D64 image on boot.
- Faster graph routines.
- EasyFlash support.
- REU support (Upcoming version will support GEORAM).
- 2MHz support for C128 in C64 mode.
- And, numerous little tweaks to make it even faster.

Performance Video

Its performance can be watched on YouTube: https://youtu.be/CkcTa5VgADM

Archive Contents

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

Supported Hardware

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.

GEOS64.D64 and GEOS64.D71 Contents

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

Known Problems

. 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.

Recommended Books

. "GEOS Tricks & Tips" by M. Kerkloh and R. Tornsdorf
. "How to Get the Most out of GEOS" by Jr. Jim Oldfield and Tim Sickbert
. "GEOS Version 2.0 Manual" by Berkeley Softworks
. "GEOS Inside and Out" by M. Tornsdorf
(You can find them at http://www.bombjack.org/commodore/books.htm#LANGUAGES_-_OS )

Recommended Links

. "GEOS Wiki" - https://www.c64-wiki.com/index.php/GEOS
. "GEOS FAQ" - http://www.zimmers.net/geos/GEOSFAQ.html
. "GEOS for the C64" - http://lyonlabs.org/commodore/onrequest/geos.html
. "GEOS CD" - http://www.lyonlabs.org/commodore/onrequest/geos/geoSpecific/
. "GEOS 64 2.0 Source Code" - https://github.com/ytmytm/c64-GEOS2000
. "GEOS 128 2.0 Source Code" - https://github.com/ytmytm/c64-GEOS128

Recommended Videos

. "GEOS 64 2.1e ROM Boots from EasyFlash" - https://youtu.be/CkcTa5VgADM
. "Booting GEOS in 10 Seconds" - https://youtu.be/EZLgPM4m_Zw
. "IRQhack64 Turbo (GEOS Boot in 4 Seconds)" - https://youtu.be/Lv3V5gn9QSA
. "Some GEOS Games" - https://youtu.be/5OT3DoPty4Y
. "PC vs C64 - GEOS DeskTop" - https://youtu.be/oh5Uql2sNa4
. "Commodore 64 Online with GEOS and GeoLink" - https://youtu.be/B-El9AbyR0w
. "GEOS + GeoTerm Dialing/Telnetting to a BBS" - https://youtu.be/Qw-wdKtCaP0