Commodore 64 emulators for the Amiga have been rumored for the past year or so. Glowing reports of these emulators have attracted a lot of interest in the Commodore community. We recently received two such products at COMPUTE!. Here are our first impressions.

Commodore 64 emulators for the Amiga are a hot topic. We recently obtained release copies of two such products for evaluation: The 64 Emulator, from ReadySoft; and GO-64!, from Software Insights Systems. This is not a product review - it is more of a preview. Both companies are still working on their software, and updates are sure to come.

Pros And Cons Of Emulation

Why a 64 emulator for the Amiga? The most obvious answer: Many 64 owners who upgrade to an Amiga are reluctant to lose their 64 software and hardware investments. Some popular 64 programs are simply not available for the Amiga, and many never will be. Also, emulation in general is intrinsically interesting - seeing the 64 startup message on the Amiga is fascinating.

On the other hand, why cripple the Amiga by turning it into a 64? Emulators are notoriously slow, and no emulator can offer 100 percent compatibility. But, if you sold your 64 in order to buy an Amiga, or if you just want some connection between your two computers, however tenuous, an emulator may prove a practical purchase.

Both emulators come with a hardware device that allows you to connect a 1541/1571 disk drive to your Amiga via the parallel port. (Actually, this hardware device is optional on The 64 Emulator, but highly recommended.) If you own an Amiga 1000, the GO-64 emulator requires a special cable that converts your parallel port to be compatible with the 500's and the 2000's. There are two different disk drive interfaces for The 64 Emulator - one for the 1000 and one for the newer models. You'll need this hardware device in order to load 64 software from disk. Neither of these products are able to load 64 software from the Amiga's 5 1/4-inch 1010 drive.

A real 64 does its magic with special hardware. The brain of the 64 is the 6510 microprocessor. The special VIC and SID chips control the video and sound effects that nearly every 64 program uses.

Essentially, these emulators are 64s on a disk. In conjunction with your Amiga computer, they translate each instruction and video and audio command into a job for the Amiga. This translation takes a great deal of time. The 68000 microprocessor in the Amiga is far faster and more powerful than the 6510 in the 64, but it's not up to the task of playing the part of a real 64 at full speed.

How Fast Do They Go?

We wrote several short programs to test the speed of the emulators. Here are the results (all times are in seconds):

        64      64     GO-64
             Emulator
Test 1  10      49       22
Test 2  44      69       93
Test 3   9      42       28
Test 4  11      48       19
Test 5   5      19       51

Test 1 was an empty BASIC loop counting to 10,000; Test 2 tested text-screen I/O; Test 3 moved a sprite around the borders of the screen; various math functions were tested by Test 4; and Test 5 was a machine language do-nothing loop.

The benchmarks tell a strange story. The 64 Emulator beats the GO-64! emulator in two tests, and loses the other three. The 64 computer itself is the only clear winner here. We had trouble with Benchmark 3 using GO-64! - we had to put a PRINT statement in our program before the sprite would appear.

Although the GO-64! emulator wins three out of five of our benchmarks, we found that most commercial programs run faster on The 64 Emulator.

Other Considerations

The GO-64! emulator does not yet support the SID chip. The 64 Emulator does, but at the slower executions speeds, a cheerful march becomes a dirge.

Sprites on The 64 Emulator are handled through use of the Amiga's virtual sprite system. This can cause the sprites to flicker when more than four sprites are displayed horizontally. Because GO-64! uses bobs (blitter objects, which are directly drawn on the screen) to emulate sprites, it does not have this problem. There is a price to pay for using bobs - vsprites are faster. The GO-64!'s screen seems to jump instead of moving smoothly.

The way in which these emulators handle the keyboard is quite different. While GO-64! tries its best to duplicate the 64 's keyboard (a quote is still SHIFT-2 and cursor keys must be shifted to move the cursor up or left), The 64 Emulator uses the Amiga's keyboard layout. We found it very frustrating on the GO-64! emulator to press right- bracket to get an asterisk. People who learned to type on the 64, however, may feel right at home. The GO-64! had trouble keeping up with fast typing.

A Better 64?

One of the advantages of the Amiga over the 64 is that it uses an RGB monitor, which provides better resolution and color than the composite monitors used by the 64. Both 64 emulators let you take advantage of your Amiga screen to see 64 graphics as they've never been seen before. If you have a favorite piece of artwork on your 64, load it up on a 64 emulator and you'll be pleasantly surprised.

The 64 Emulator has a control panel with some interesting options. You can choose to use your Amiga mouse to emulate a 1530 or 1531 mouse for your 64, In addition, you can use your ramdisk and Amiga disk drives from 64 mode with The 64 Emulator. This is great for transferring text files from one computer to another. The 64 Emulator is also able to emulate the 1764 ram expansion unit.

Compatibility

We tested several popular programs on both emulators with mixed results. Both products were able to run GEOS, with The 64 Emulator running it a bit faster. SpeedScript ran on The 64 Emulator, but not on GO-64!. "MetaBASIC," COMPUTE!'s popular BASIC programming utility, would not run on either. If you have specific software that you want to run on your emulator, be sure to try it out at a computer store first.

To ensure the highest possible compatibility, producers of the GO-64! emulator suggest that you transfer the ROMs from a 64 to your GO-64! disk. This process requires telecommunications software and modems for each computer. We used the 64 ROMs for all of our tests. If you choose not to copy the ROMs, the emulator will still work.

by Rhett Anderson and Randy Thompson

GO-64!
Software Insight Systems
16E International Dr.
East Granby, CT 06026
$69.95


The 64 Emulator
Readysoft
P.O. Box 1222
Lewiston, NY 14092
$39.95
$59.95 for serial interface

ref.: Rhett Anderson and Randy Thompson, "Two 64 Emulators for the Amiga", Compute!, February 1988, Issue 93, pp.80-81

Rhett Anderson
01.02.1988

Keywords: Commodore, Amiga, C64, Commodore 64, Software, Emulator