Amiga 500 Rev. 8a.1 mobo. Pro's/Con's?

[Oldsmobile_Mike]

Although officially introduced in 1992, some Amiga 500 Plus units had already been sold (masquerading as Amiga 500 models, and with no prior announcement) during late 1991. It has been speculated that Commodore had already sold out the remaining stocks of Amiga 500s, before the run up to the profitable Christmas sales period. In order to make enough A500s before Christmas, Commodore used stocks of the new 8A revision motherboards destined for the A500+. Many users were unaware that they were purchasing anything other than a standard Amiga 500. Although the Amiga 500+ was an improvement to the Amiga 500, it was minor. It was discontinued and replaced by the Amiga 600 in summer 1992, making it the shortest lived Amiga model.

https://en.wikipedia.org/wiki/Amiga_500_Plus

My opinion:  Good find!  You're lucky it doesn't have a leaky battery.  If it were me, I'd bump it up to 2MB of chip ram, throw in 8MB of fast, a 68010, 3.1, stick some kind of CF or MicroSD card solution on there, maybe an Indivision, and use it as a WHDLoad machine.  Probably the most desirable of all A500-class models since it needs the least amount of work to add things like that 2MB chip ram upgrade.  But that's just my .02 cents, ymmv.

PS - if it's NTSC let me know if you'd like to sell it.  

[Oldsmobile_Mike]

My machine has 512kb of Chip Ram. And it was never fitted with a battery. So my guess is that it was 500+ boards, refitted to meet the original 500 spec's as close as possible.

Adding something like this should give you 1.5MB of chip:

https://www.ebay.com/itm/Amiga-500-500-512KB-1MB-memory-RAM-expansion-trapdoor-board-like-A501-/252934142608?var=&hash=item3ae40cba90

You may want to verify fully that you have the latest 8375 Agnus (to address 2MB), but considering you have the 8A motherboard you should.  Fill the unoccupied spots on the motherboard to bump yourself up to the full 2MB.

[Oldsmobile_Mike]

I think I have read somewere, that trapdoor ram, used as chipram is not the fastest solution. Will there be differences in speed between upgraded chipram on the board versus chipram in the trapdoor?

I think you misunderstand the difference between chip ram and fast ram. True, chip ram is not as fast as fast ram (which, on an A500 typically sits under the CPU or in the expansion slot on the side), however it is directly addressable by the custom chips - which means you can (generally) load larger mods, open screens with higher resolutions and more colors, play games with more graphic objects, etc. A loose analogy is to think of it sort of like the difference between motherboard ram on a modern PC and graphics card ram.

Note that this is different from cards like the AdRAM, which add additional memory physically inside the trap door slot and call it "fast ram" but which don't actually provide the speed boost of real fast ram.

TL;DR. It's best if you can max out both your chip and your fast ram, budget permitting, of course.

[Oldsmobile_Mike]

Expansion slot ram will be "slow" fast ram. If you have a 2 mb Agnus, it's better to fill the mobo and leave the expansion alone.

A500+ should be able to address up to 1MB of chip through the motherboard and 1MB through the trapdoor.

http://www.amiga.org/forums/showthread.php?t=69106

(unless you do something "crazy" like piggyback chips hack, etc.)