Classic Computer Magazine Archive COMPUTE! ISSUE 76 / SEPTEMBER 1986 / PAGE 10

Reader's Feedback

The Editors and Readers of COMPUTE!

If you have any questions, comments, or suggestions you would like to see addressed in this column, write to "Readers' Feedback," COMPUTE!, P.O. Box 5406, Greensboro, NC 27403. Due to the volume of mail we receive, we regret that we cannot provide personal answers to technical questions.

IBM PrtSc Problems

When using the PrtSc function with my PCjr in "IBM Pie Chart Maker" (COMPUTE!, January 1985), my Gemini 10X prints the chart, but with thin blank lines between each row of the chart, as if the printer were displaying text lines. I have tried resetting the line space command to the printer and tested it in immediate mode to verify that the line space has been changed. But as soon as I type the PrtSc command, it seems that this command initializes the printer.

Rich Camaish

We've experienced the same problem when using PrtSc with anything except an Epson printer. Normally, pressing SHIFT-PrtSc just prints a text dump. In order to dump graphics with PrtSc, you need to enter the GRAPHICS command at the DOS command line to load the graphics print-screen driver. This driver was written specifically for the IBM Graphics Printer, a relabeled version of the Epson MX-80.

Apparently, the driver resets the printer completely before starting the graphics dump, as if the printer were turned off and on. (The Epson code for this is ESC-@.) It then sets the lines-per-inch to 8, corresponding to seamless eight-wire graphics printing. The code used for this function is different on the Gemini 10X and many other printers that are otherwise Epson compatible. Your printer accepts the reset sequence, though, throwing it back to nine lines per inch before starting the graphics dump. We've had the same problem with the IBM Color Printer.

The only way around this would be to modify the GRAPHICS driver. If you know something about 8088 machine language and have a working acquaintance with the DEBUG utility, you could search for the ESC-@ sequence (hex $1F $40) and replace it with two zeros to null it out. However, there are programs on the market and in the public domain that support graphics printing with PrtSc for many different printers. Check with your local IBM user group or nearest dealer to see if they've heard of these.