| Business | Phone |
| National Micro Systems Inc 2 E 8th St 100, Chicago 60605 | (312) 939-3035 |
| Nova Computers Inc 5245 N Harlem Ave, Chicago 60656 | (773) 774-9915 |
| Hewlett-Packard 100 N Riverside Plz, Chicago 60606 | (312) 474-4000 |
| Juster Chicago Computer Inc 5404 N Natchez Ave, Chicago 60656 | (773) 631-7801 |