A500 Accelerators

ID #3099

CMI (Creative Microsystems Inc): PAMC-500

Connection: CPU Socket


Processor:68000@14Mhz switchable to 7Mhz
FPU:Optional 68881 (a separate crystal must be obtained)
Max Ram:None
Ram Type:Does not have support for adding RAM.

An accelerator board designed for the A500 which sits in the CPU socket. This card is also compatible with the A2000 however it's dimensions mean that it may hang over the A2000's battery requiring some method to raise the card high enough. The PAMC-500 (unlike the PAMC-2000) has special notches cut into the PCB to stop it hanging over the Agnus, allowing for the Megachip to be installed. It still however covers the Kickstart chips meaning you may have difficulty using a ROM switcher. The card can be set to either 14Mhz or 7Mhz using the software provided (PA), dropping to 7Mhz is to help with any backwards compatibility problems. Replacement Workbench 1.3 maths libraries are supplied (providing you are using WB1.3) to take advantage of the FPU if one is fitted.


J1: Fast ROM

When the two jumper pins are shorted, the accelerator runs in "Fast ROM" mode where the Kickstart ROM is accessed with a reduced number of wait-states when the processor is running at 14Mhz. Some A500's and A2000's with Kickstart 1.3 are not able to handle this feature, and the jumper should be disabled.

J2: Forced 14 Jumper

Normally the PA program is used to switch the clock speed to 14MHz. This can be done using a project icon, or added to the startup-sequence. However, some self-booting games do not execute a startup sequence, and some users wish to run at 14mhz at all times. The jumper has 2 potitions, but pin 1 is not marked. Looking at the jumper with the (Jumper) 2 identifier upright, the right and middle pins jumpered will allow the processor to be switched between 7 and 14mhz using the software. The middle and left pins jumpered will force the processor to run at 14Mhz at all times.

Contributions to this page by:
Michael Mellendorf, Ron Mascaro

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Last update: 2009-01-25 12:59
Revision: 1.0

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