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D > DIGITAL EQUIPMENT CORPORATION > 300 Professional series


Digital Equipment Corporation
300 Professional series

William Smith, who still own a DEC Pro 350, reports to us:
The video was really weird (but not as weird as the Apple //e with the Extended 80-column card). There were two ways to do color (or at least gray-scale).  The normal way was to buy the Extended Bitmap Option (EBO) board, which on the Pro 325 and 350 gave you three planes of video (8 simultaneous colors) from an 8-bit palette (256 possible RGB colors, with 3 bits for red, 3 bits for green, and 2 bits for blue).  The Pro 380's EBO board gave 3 planes of video from a 12-bit palette (4096 possible RGB colors, with 4 bits each for red, green , and blue).  Also, the Pro 325/350 EBO board was a normal expansion card, while the Pro 380 EBO board was a daughter card which plugged directly into the motherboard, thus saving a slot.

The second way to get "color" (it was really gray-scale) was to use an alternate video mode which traded resolution for color.  For a monochrome system (one video plane), the normal video mode was black and white at 1024x256, of which 960x240 was available to the application.  The two alternate video modes gave 4 or 16 simultaneous shades of gray by reducing the resolution to 512x256 or 256x256, respectively.  These video modes were never used on any commercial software (that I know of, anyway).

It was also possible to use these alternate video modes in combination with an EBO board, which gave 4096 simultaneous RGB colors at 256x256 pixels (on a color monitor, which I didn't have).

_______________________

About the number of expansion cards in the base systems.  All Pro 300 series machines had six expansion slots, configured as follows:

Pro 325
1: empty (Pro 325 + hard disk = Pro 350)
2: floppy disk controller
3: standard video controller
4: empty
5: 256KB memory (+ 256KB on mobo = 512KB)
6: empty

Pro 350
1: hard disk controller
2: floppy disk controller
3: standard video controller
4: empty (I had the optional EBO board)
5: 256KB memory (+ 256KB on mobo = 512KB)
6: empty (I had an Ethernet board here)

Pro 380
1: hard disk controller
2: floppy disk controller
3: empty (standard video was on the motherboard)
4: empty
5: empty (512KB all on the motherboard)
6: empty





 
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